21521325 has 24 divisors (see below), whose sum is σ = 40666048. Its totient is φ = 9838080.

The previous prime is 21521323. The next prime is 21521329. The reversal of 21521325 is 52312512.

It is not a de Polignac number, because 21521325 - 2¹ = 21521323 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521321) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19972 + ... + 21021.

Almost surely, 2^21521325 is an apocalyptic number.

21521325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21521325 is a deficient number, since it is larger than the sum of its proper divisors (19144723).

21521325 is a wasteful number, since it uses less digits than its factorization.

21521325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41013 (or 41008 counting only the distinct ones).

The product of its digits is 600, while the sum is 21.

The square root of 21521325 is about 4639.1082117148. The cubic root of 21521325 is about 278.1567918041.

Adding to 21521325 its reverse (52312512), we get a palindrome (73833837).

The spelling of 21521325 in words is "twenty-one million, five hundred twenty-one thousand, three hundred twenty-five".