21115560 has 32 divisors (see below), whose sum is σ = 63347040. Its totient is φ = 5630784.

The previous prime is 21115559. The next prime is 21115573. The reversal of 21115560 is 6551112.

It is a super-2 number, since 2×21115560² = 891733748227200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87862 + ... + 88101.

It is an arithmetic number, because the mean of its divisors is an integer number (1979595).

Almost surely, 2^21115560 is an apocalyptic number.

21115560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21115560 is an abundant number, since it is smaller than the sum of its proper divisors (42231480).

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

21115560 is a wasteful number, since it uses less digits than its factorization.

21115560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175977 (or 175973 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 21.

The square root of 21115560 is about 4595.1670263441. The cubic root of 21115560 is about 276.3975577172.

Adding to 21115560 its reverse (6551112), we get a palindrome (27666672).

The spelling of 21115560 in words is "twenty-one million, one hundred fifteen thousand, five hundred sixty".