21572256 has 24 divisors (see below), whose sum is σ = 56627424. Its totient is φ = 7190720.

The previous prime is 21572251. The next prime is 21572261. The reversal of 21572256 is 65227512.

It is an interprime number because it is at equal distance from previous prime (21572251) and next prime (21572261).

It is a tau number, because it is divible by the number of its divisors (24).

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21572251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 112260 + ... + 112451.

It is an arithmetic number, because the mean of its divisors is an integer number (2359476).

Almost surely, 2^21572256 is an apocalyptic number.

It is an amenable number.

21572256 is an abundant number, since it is smaller than the sum of its proper divisors (35055168).

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

21572256 is a wasteful number, since it uses less digits than its factorization.

21572256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224724 (or 224716 counting only the distinct ones).

The product of its digits is 8400, while the sum is 30.

The square root of 21572256 is about 4644.5942772216. The cubic root of 21572256 is about 278.3760416693.

Adding to 21572256 its reverse (65227512), we get a palindrome (86799768).

The spelling of 21572256 in words is "twenty-one million, five hundred seventy-two thousand, two hundred fifty-six".