21312691808 has 24 divisors (see below), whose sum is σ = 41989230360. Its totient is φ = 10648760320.

The previous prime is 21312691739. The next prime is 21312691823. The reversal of 21312691808 is 80819621312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 191258 + ... + 281433.

It is an arithmetic number, because the mean of its divisors is an integer number (1749551265).

Almost surely, 2^21312691808 is an apocalyptic number.

It is an amenable number.

21312691808 is a deficient number, since it is larger than the sum of its proper divisors (20676538552).

21312691808 is a wasteful number, since it uses less digits than its factorization.

21312691808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 474110 (or 474102 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 41.

The spelling of 21312691808 in words is "twenty-one billion, three hundred twelve million, six hundred ninety-one thousand, eight hundred eight".