21556320 has 48 divisors (see below), whose sum is σ = 67903920. Its totient is φ = 5748224.

The previous prime is 21556273. The next prime is 21556321. The reversal of 21556320 is 2365512.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556321) 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, 21975 + ... + 22934.

It is an arithmetic number, because the mean of its divisors is an integer number (1414665).

Almost surely, 2^21556320 is an apocalyptic number.

21556320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21556320 is an abundant number, since it is smaller than the sum of its proper divisors (46347600).

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

21556320 is a wasteful number, since it uses less digits than its factorization.

21556320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44927 (or 44919 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 24.

The square root of 21556320 is about 4642.8784175337. The cubic root of 21556320 is about 278.3074768511.

The spelling of 21556320 in words is "twenty-one million, five hundred fifty-six thousand, three hundred twenty".