21158560 has 24 divisors (see below), whose sum is σ = 49987476. Its totient is φ = 8463360.

The previous prime is 21158549. The next prime is 21158563. The reversal of 21158560 is 6585112.

It can be written as a sum of positive squares in 2 ways, for example, as 21123216 + 35344 = 4596^2 + 188^2 .

It is a super-2 number, since 2×21158560² = 895369322547200, which contains 22 as substring.

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21158563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65961 + ... + 66280.

Almost surely, 2^21158560 is an apocalyptic number.

21158560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21158560 is an abundant number, since it is smaller than the sum of its proper divisors (28828916).

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

21158560 is a wasteful number, since it uses less digits than its factorization.

21158560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132256 (or 132248 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 28.

The square root of 21158560 is about 4599.8434755978. The cubic root of 21158560 is about 276.5850503599.

The spelling of 21158560 in words is "twenty-one million, one hundred fifty-eight thousand, five hundred sixty".