Nearly 21 percent of Americans 65 and older have difficulty with at least one aspect of everyday life, according to estimates from the federal Agency for Health Care Policy and Research.

A survey of 37,000 people conducted in 1987 shows that 13 percent of the elderly who live outside of institutions -- 3.6 million people -- have trouble walking or with basic hygiene tasks such as bathing, toileting and dressing. Approximately 18 percent, or 5 million, need help with social functions such as shopping, cleaning house, cooking and managing money, the survey found.

The most frequent personal care problem is bathing, followed by getting into or out of a chair or bed. The most common difficulty people have functioning in public involves mobility: 3.8 million, nearly 13.5 percent, have problems with driving a car or using public transportation; 2.2 million elderly, nearly 8 percent, have difficulty walking.

While relatively few people ages 55 to 64 were found to have trouble with daily tasks, the rate increases after age 65 and climbs sharply after age 80. Many older people whose abilities are limited require personal assistance or rely on equipment such as walkers or wheelchairs. Relatively high rates of impairment were found among people living alone.

TASK ............... PERSONS OVER 65 AFFECTED .... PERCENT

USING TELEPHONE ................ 1,237,000 ........... 4.4

HANDLING MONEY ................. 1,758,000 ........... 6.3

SHOPPING ....................... 3,072,000 .......... 11.0

GETTING AROUND THE COMMUNITY ... 3,774,000 .......... 13.5

PREPARING MEALS ................ 2,090,000 ........... 7.5

LIGHT HOUSE CLEANING ........... 2,823,000 .......... 10.1

SOURCE: Department of Health and Human Services, National Medical Expenditure Survey, June 1990