21153625 has 32 divisors (see below), whose sum is σ = 28035072. Its totient is φ = 15912000.

The previous prime is 21153623. The next prime is 21153637. The reversal of 21153625 is 52635112.

It is not a de Polignac number, because 21153625 - 2¹ = 21153623 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21153625.

It is not an unprimeable number, because it can be changed into a prime (21153623) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 205324 + ... + 205426.

It is an arithmetic number, because the mean of its divisors is an integer number (876096).

Almost surely, 2^21153625 is an apocalyptic number.

21153625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21153625 is a deficient number, since it is larger than the sum of its proper divisors (6881447).

21153625 is a wasteful number, since it uses less digits than its factorization.

21153625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202 (or 192 counting only the distinct ones).

The product of its digits is 1800, while the sum is 25.

The square root of 21153625 is about 4599.3070130184. The cubic root of 21153625 is about 276.5635452204.

Adding to 21153625 its reverse (52635112), we get a palindrome (73788737).

The spelling of 21153625 in words is "twenty-one million, one hundred fifty-three thousand, six hundred twenty-five".