21282920 has 32 divisors (see below), whose sum is σ = 48205800. Its totient is φ = 8456448.

The previous prime is 21282901. The next prime is 21282923. The reversal of 21282920 is 2928212.

It can be written as a sum of positive squares in 4 ways, for example, as 19838116 + 1444804 = 4454^2 + 1202^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21282920.

It is not an unprimeable number, because it can be changed into a prime (21282923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4586 + ... + 7974.

Almost surely, 2^21282920 is an apocalyptic number.

21282920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21282920 is an abundant number, since it is smaller than the sum of its proper divisors (26922880).

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

21282920 is a wasteful number, since it uses less digits than its factorization.

21282920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3557 (or 3553 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21282920 is about 4613.3415221507. The cubic root of 21282920 is about 277.1258708445.

The spelling of 21282920 in words is "twenty-one million, two hundred eighty-two thousand, nine hundred twenty".