21513525 has 48 divisors (see below), whose sum is σ = 39372480. Its totient is φ = 10278400.

The previous prime is 21513523. The next prime is 21513559. The reversal of 21513525 is 52531512.

It is a happy number.

It is not a de Polignac number, because 21513525 - 2¹ = 21513523 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21513495 and 21513504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513523) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 73279 + ... + 73571.

It is an arithmetic number, because the mean of its divisors is an integer number (820260).

Almost surely, 2^21513525 is an apocalyptic number.

21513525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21513525 is a deficient number, since it is larger than the sum of its proper divisors (17858955).

21513525 is a wasteful number, since it uses less digits than its factorization.

21513525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406 (or 401 counting only the distinct ones).

The product of its digits is 1500, while the sum is 24.

The square root of 21513525 is about 4638.2674567127. The cubic root of 21513525 is about 278.1231835087.

The spelling of 21513525 in words is "twenty-one million, five hundred thirteen thousand, five hundred twenty-five".