21532720 has 40 divisors (see below), whose sum is σ = 54617040. Its totient is φ = 7829760.

The previous prime is 21532717. The next prime is 21532733. The reversal of 21532720 is 2723512.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21532691 and 21532700.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11355 + ... + 13114.

It is an arithmetic number, because the mean of its divisors is an integer number (1365426).

Almost surely, 2^21532720 is an apocalyptic number.

21532720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21532720 is an abundant number, since it is smaller than the sum of its proper divisors (33084320).

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

21532720 is a wasteful number, since it uses less digits than its factorization.

21532720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24493 (or 24487 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21532720 is about 4640.3361947169. The cubic root of 21532720 is about 278.2058754827.

The spelling of 21532720 in words is "twenty-one million, five hundred thirty-two thousand, seven hundred twenty".