21705214836 has 48 divisors (see below), whose sum is σ = 53807927040. Its totient is φ = 6796782720.

The previous prime is 21705214819. The next prime is 21705214859. The reversal of 21705214836 is 63841250712.

It is a super-2 number, since 2×21705214836² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21705214794 and 21705214803.

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 15 ways as a sum of consecutive naturals, for example, 829980 + ... + 855731.

It is an arithmetic number, because the mean of its divisors is an integer number (1120998480).

Almost surely, 2^21705214836 is an apocalyptic number.

It is an amenable number.

21705214836 is an abundant number, since it is smaller than the sum of its proper divisors (32102712204).

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

21705214836 is a wasteful number, since it uses less digits than its factorization.

21705214836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1685784 (or 1685782 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 39.

The spelling of 21705214836 in words is "twenty-one billion, seven hundred five million, two hundred fourteen thousand, eight hundred thirty-six".