21668872978708 has 6 divisors (see below), whose sum is σ = 37920527712746. Its totient is φ = 10834436489352.

The previous prime is 21668872978667. The next prime is 21668872978721. The reversal of 21668872978708 is 80787927886612.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21349408373764 + 319464604944 = 4620542^2 + 565212^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2708609122335 + ... + 2708609122342.

Almost surely, 2^{21668872978708} is an apocalyptic number.

It is an amenable number.

21668872978708 is a deficient number, since it is larger than the sum of its proper divisors (16251654734038).

21668872978708 is a wasteful number, since it uses less digits than its factorization.

21668872978708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5417218244681 (or 5417218244679 counting only the distinct ones).

The product of its (nonzero) digits is 1820786688, while the sum is 79.

The spelling of 21668872978708 in words is "twenty-one trillion, six hundred sixty-eight billion, eight hundred seventy-two million, nine hundred seventy-eight thousand, seven hundred eight".