21569625 has 128 divisors (see below), whose sum is σ = 50319360. Its totient is φ = 8856000.

The previous prime is 21569623. The next prime is 21569629. The reversal of 21569625 is 52696512.

21569625 is a `hidden beast` number, since 21 + 5 + 6 + 9 + 625 = 666.

It is not a de Polignac number, because 21569625 - 2¹ = 21569623 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21569625.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21569621) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 259834 + ... + 259916.

It is an arithmetic number, because the mean of its divisors is an integer number (393120).

Almost surely, 2^21569625 is an apocalyptic number.

21569625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21569625 is an abundant number, since it is smaller than the sum of its proper divisors (28749735).

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

21569625 is a wasteful number, since it uses less digits than its factorization.

21569625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 109 counting only the distinct ones).

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

The square root of 21569625 is about 4644.3110360957. The cubic root of 21569625 is about 278.3647240901.

It can be divided in two parts, 2156 and 9625, that added together give a triangular number (11781 = T₁₅₃).

The spelling of 21569625 in words is "twenty-one million, five hundred sixty-nine thousand, six hundred twenty-five".