21320900 has 18 divisors (see below), whose sum is σ = 46266570. Its totient is φ = 8528320.

The previous prime is 21320881. The next prime is 21320911. The reversal of 21320900 is 902312.

It can be written as a sum of positive squares in 3 ways, for example, as 399424 + 20921476 = 632^2 + 4574^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 106505 + ... + 106704.

It is an arithmetic number, because the mean of its divisors is an integer number (2570365).

Almost surely, 2^21320900 is an apocalyptic number.

21320900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21320900 is an abundant number, since it is smaller than the sum of its proper divisors (24945670).

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

21320900 is a wasteful number, since it uses less digits than its factorization.

21320900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213223 (or 213216 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 21320900 is about 4617.4560095360. The cubic root of 21320900 is about 277.2906193205.

The spelling of 21320900 in words is "twenty-one million, three hundred twenty thousand, nine hundred".