21625956 has 72 divisors (see below), whose sum is σ = 60357024. Its totient is φ = 6474240.

The previous prime is 21625951. The next prime is 21625963. The reversal of 21625956 is 65952612.

21625956 is a `hidden beast` number, since 2 + 1 + 62 + 595 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21625956.

It is not an unprimeable number, because it can be changed into a prime (21625951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38131 + ... + 38693.

It is an arithmetic number, because the mean of its divisors is an integer number (838292).

Almost surely, 2^21625956 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21625956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30178512).

21625956 is an abundant number, since it is smaller than the sum of its proper divisors (38731068).

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

21625956 is a wasteful number, since it uses less digits than its factorization.

21625956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681 (or 676 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 21625956 is about 4650.3715980554. The cubic root of 21625956 is about 278.6068382151.

It can be divided in two parts, 2162 and 5956, that added together give a palindrome (8118).

The spelling of 21625956 in words is "twenty-one million, six hundred twenty-five thousand, nine hundred fifty-six".