21877929 has 12 divisors (see below), whose sum is σ = 33460596. Its totient is φ = 13727232.

The previous prime is 21877903. The next prime is 21877931. The reversal of 21877929 is 92977812.

It can be written as a sum of positive squares in 2 ways, for example, as 17264025 + 4613904 = 4155^2 + 2148^2 .

It is not a de Polignac number, because 21877929 - 2⁵ = 21877897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21877939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71344 + ... + 71649.

It is an arithmetic number, because the mean of its divisors is an integer number (2788383).

Almost surely, 2^21877929 is an apocalyptic number.

It is an amenable number.

21877929 is a deficient number, since it is larger than the sum of its proper divisors (11582667).

21877929 is a wasteful number, since it uses less digits than its factorization.

21877929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143016 (or 143013 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 21877929 is about 4677.3848462576. The cubic root of 21877929 is about 279.6847174010.

The spelling of 21877929 in words is "twenty-one million, eight hundred seventy-seven thousand, nine hundred twenty-nine".