21631875 has 40 divisors (see below), whose sum is σ = 36738240. Its totient is φ = 11316000.

The previous prime is 21631867. The next prime is 21631879. The reversal of 21631875 is 57813612.

It is not a de Polignac number, because 21631875 - 2³ = 21631867 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631879) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 155556 + ... + 155694.

It is an arithmetic number, because the mean of its divisors is an integer number (918456).

Almost surely, 2^21631875 is an apocalyptic number.

21631875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21631875 is a deficient number, since it is larger than the sum of its proper divisors (15106365).

21631875 is an equidigital number, since it uses as much as digits as its factorization.

21631875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245 (or 230 counting only the distinct ones).

The product of its digits is 10080, while the sum is 33.

The square root of 21631875 is about 4651.0079552716. The cubic root of 21631875 is about 278.6322540233.

The spelling of 21631875 in words is "twenty-one million, six hundred thirty-one thousand, eight hundred seventy-five".