21513875 has 16 divisors (see below), whose sum is σ = 27112800. Its totient is φ = 17042400.

The previous prime is 21513859. The next prime is 21513887. The reversal of 21513875 is 57831512.

It is not a de Polignac number, because 21513875 - 2⁴ = 21513859 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12836 + ... + 14414.

It is an arithmetic number, because the mean of its divisors is an integer number (1694550).

Almost surely, 2^21513875 is an apocalyptic number.

21513875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21513875 is a deficient number, since it is larger than the sum of its proper divisors (5598925).

21513875 is a wasteful number, since it uses less digits than its factorization.

21513875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1703 (or 1693 counting only the distinct ones).

The product of its digits is 8400, while the sum is 32.

The square root of 21513875 is about 4638.3051861644. The cubic root of 21513875 is about 278.1246917473.

The spelling of 21513875 in words is "twenty-one million, five hundred thirteen thousand, eight hundred seventy-five".