21879836 has 12 divisors (see below), whose sum is σ = 41770680. Its totient is φ = 9945360.

The previous prime is 21879827. The next prime is 21879841. The reversal of 21879836 is 63897812.

21879836 is nontrivially palindromic in base 13.

It is a Harshad number since it is a multiple of its sum of digits (44), and also a Moran number because the ratio is a prime number: 497269 = 21879836 / (2 + 1 + 8 + 7 + 9 + 8 + 3 + 6).

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 248591 + ... + 248678.

It is an arithmetic number, because the mean of its divisors is an integer number (3480890).

Almost surely, 2^21879836 is an apocalyptic number.

It is an amenable number.

21879836 is a deficient number, since it is larger than the sum of its proper divisors (19890844).

21879836 is a wasteful number, since it uses less digits than its factorization.

21879836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497284 (or 497282 counting only the distinct ones).

The product of its digits is 145152, while the sum is 44.

The square root of 21879836 is about 4677.5886950436. The cubic root of 21879836 is about 279.6928434484.

The spelling of 21879836 in words is "twenty-one million, eight hundred seventy-nine thousand, eight hundred thirty-six".