21636875 has 20 divisors (see below), whose sum is σ = 29128176. Its totient is φ = 15972000.

The previous prime is 21636851. The next prime is 21636887. The reversal of 21636875 is 57863612.

It is not a de Polignac number, because 21636875 - 2⁸ = 21636619 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6794 + ... + 9456.

Almost surely, 2^21636875 is an apocalyptic number.

21636875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21636875 is a deficient number, since it is larger than the sum of its proper divisors (7491301).

21636875 is an equidigital number, since it uses as much as digits as its factorization.

21636875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2696 (or 2681 counting only the distinct ones).

The product of its digits is 60480, while the sum is 38.

The square root of 21636875 is about 4651.5454421085. The cubic root of 21636875 is about 278.6537200920.

The spelling of 21636875 in words is "twenty-one million, six hundred thirty-six thousand, eight hundred seventy-five".