21658877668 has 6 divisors (see below), whose sum is σ = 37903035926. Its totient is φ = 10829438832.

The previous prime is 21658877623. The next prime is 21658877671. The reversal of 21658877668 is 86677885612.

It can be written as a sum of positive squares in only one way, i.e., 21559636224 + 99241444 = 146832^2 + 9962^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2707359705 + ... + 2707359712.

Almost surely, 2^21658877668 is an apocalyptic number.

It is an amenable number.

21658877668 is a deficient number, since it is larger than the sum of its proper divisors (16244158258).

21658877668 is a wasteful number, since it uses less digits than its factorization.

21658877668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5414719421 (or 5414719419 counting only the distinct ones).

The product of its digits is 54190080, while the sum is 64.

The spelling of 21658877668 in words is "twenty-one billion, six hundred fifty-eight million, eight hundred seventy-seven thousand, six hundred sixty-eight".