21391733756 has 48 divisors (see below), whose sum is σ = 39933855360. Its totient is φ = 9997479360.

The previous prime is 21391733749. The next prime is 21391733773. The reversal of 21391733756 is 65733719312.

It is a self number, because there is not a number n which added to its sum of digits gives 21391733756.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5971886 + ... + 5975466.

It is an arithmetic number, because the mean of its divisors is an integer number (831955320).

Almost surely, 2^21391733756 is an apocalyptic number.

It is an amenable number.

21391733756 is a deficient number, since it is larger than the sum of its proper divisors (18542121604).

21391733756 is a wasteful number, since it uses less digits than its factorization.

21391733756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4634 (or 4632 counting only the distinct ones).

The product of its digits is 714420, while the sum is 47.

The spelling of 21391733756 in words is "twenty-one billion, three hundred ninety-one million, seven hundred thirty-three thousand, seven hundred fifty-six".