21649923816 has 32 divisors (see below), whose sum is σ = 54204798240. Its totient is φ = 7205976128.

The previous prime is 21649923773. The next prime is 21649923821. The reversal of 21649923816 is 61832994612.

It is a hoax number, since the sum of its digits (51) coincides with the sum of the digits of its distinct prime factors.

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 7 ways as a sum of consecutive naturals, for example, 649986 + ... + 682481.

It is an arithmetic number, because the mean of its divisors is an integer number (1693899945).

Almost surely, 2^21649923816 is an apocalyptic number.

It is an amenable number.

21649923816 is an abundant number, since it is smaller than the sum of its proper divisors (32554874424).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21649923816 is a wasteful number, since it uses less digits than its factorization.

21649923816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333153 (or 1333149 counting only the distinct ones).

The product of its digits is 1119744, while the sum is 51.

The spelling of 21649923816 in words is "twenty-one billion, six hundred forty-nine million, nine hundred twenty-three thousand, eight hundred sixteen".