21137908 has 24 divisors (see below), whose sum is σ = 41658624. Its totient is φ = 9297600.

The previous prime is 21137891. The next prime is 21137911. The reversal of 21137908 is 80973112.

It is a super-3 number, since 3×21137908³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a self number, because there is not a number n which added to its sum of digits gives 21137908.

It is a congruent 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 7 ways as a sum of consecutive naturals, for example, 6385 + ... + 9112.

It is an arithmetic number, because the mean of its divisors is an integer number (1735776).

Almost surely, 2^21137908 is an apocalyptic number.

It is an amenable number.

21137908 is a deficient number, since it is larger than the sum of its proper divisors (20520716).

21137908 is a wasteful number, since it uses less digits than its factorization.

21137908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15543 (or 15541 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21137908 is about 4597.5980685571. The cubic root of 21137908 is about 276.4950333031.

The spelling of 21137908 in words is "twenty-one million, one hundred thirty-seven thousand, nine hundred eight".