21102920 has 32 divisors (see below), whose sum is σ = 49982400. Its totient is φ = 7996608.

The previous prime is 21102919. The next prime is 21102931. The reversal of 21102920 is 2920112.

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, 13124 + ... + 14643.

It is an arithmetic number, because the mean of its divisors is an integer number (1561950).

Almost surely, 2^21102920 is an apocalyptic number.

21102920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21102920 is an abundant number, since it is smaller than the sum of its proper divisors (28879480).

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

21102920 is a wasteful number, since it uses less digits than its factorization.

21102920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27797 (or 27793 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21102920 is about 4593.7914623979. The cubic root of 21102920 is about 276.3423951976.

It can be divided in two parts, 21102 and 920, that added together give a palindrome (22022).

The spelling of 21102920 in words is "twenty-one million, one hundred two thousand, nine hundred twenty".