21587796 has 30 divisors (see below), whose sum is σ = 56435610. Its totient is φ = 7195824.

The previous prime is 21587791. The next prime is 21587809. The reversal of 21587796 is 69778512.

It can be written as a sum of positive squares in only one way, i.e., 16112196 + 5475600 = 4014^2 + 2340^2 .

It is a super-2 number, since 2×21587796² = 932065872275232, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21587791) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 32991 + ... + 33638.

It is an arithmetic number, because the mean of its divisors is an integer number (1881187).

Almost surely, 2^21587796 is an apocalyptic number.

It is an amenable number.

21587796 is an abundant number, since it is smaller than the sum of its proper divisors (34847814).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21587796 is a wasteful number, since it uses less digits than its factorization.

21587796 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66645 (or 66634 counting only the distinct ones).

The product of its digits is 211680, while the sum is 45.

The square root of 21587796 is about 4646.2668885892. The cubic root of 21587796 is about 278.4428701818.

The spelling of 21587796 in words is "twenty-one million, five hundred eighty-seven thousand, seven hundred ninety-six".