21979875 has 16 divisors (see below), whose sum is σ = 36575136. Its totient is φ = 11722400.

The previous prime is 21979849. The next prime is 21979877. The reversal of 21979875 is 57897912.

It is not a de Polignac number, because 21979875 - 2¹⁶ = 21914339 is a prime.

It is a super-2 number, since 2×21979875² = 966229810031250, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21979877) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28932 + ... + 29681.

It is an arithmetic number, because the mean of its divisors is an integer number (2285946).

Almost surely, 2^21979875 is an apocalyptic number.

21979875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21979875 is a deficient number, since it is larger than the sum of its proper divisors (14595261).

21979875 is an equidigital number, since it uses as much as digits as its factorization.

21979875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58631 (or 58621 counting only the distinct ones).

The product of its digits is 317520, while the sum is 48.

The square root of 21979875 is about 4688.2699367677. The cubic root of 21979875 is about 280.1184660273.

The spelling of 21979875 in words is "twenty-one million, nine hundred seventy-nine thousand, eight hundred seventy-five".