21529988 has 12 divisors (see below), whose sum is σ = 37949520. Its totient is φ = 10687272.

The previous prime is 21529979. The next prime is 21529997. The reversal of 21529988 is 88992512.

It is an interprime number because it is at equal distance from previous prime (21529979) and next prime (21529997).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18806 + ... + 19917.

It is an arithmetic number, because the mean of its divisors is an integer number (3162460).

Almost surely, 2^21529988 is an apocalyptic number.

It is an amenable number.

21529988 is a deficient number, since it is larger than the sum of its proper divisors (16419532).

21529988 is a wasteful number, since it uses less digits than its factorization.

21529988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38866 (or 38864 counting only the distinct ones).

The product of its digits is 103680, while the sum is 44.

The square root of 21529988 is about 4640.0418101565. The cubic root of 21529988 is about 278.1941090392.

It can be divided in two parts, 215 and 29988, that added together give a palindrome (30203).

The spelling of 21529988 in words is "twenty-one million, five hundred twenty-nine thousand, nine hundred eighty-eight".