21317972838 has 16 divisors (see below), whose sum is σ = 43058084976. Its totient is φ = 7035634400.

The previous prime is 21317972801. The next prime is 21317972861. The reversal of 21317972838 is 83827971312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17588481 + ... + 17589692.

It is an arithmetic number, because the mean of its divisors is an integer number (2691130311).

Almost surely, 2^21317972838 is an apocalyptic number.

21317972838 is an abundant number, since it is smaller than the sum of its proper divisors (21740112138).

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

21317972838 is a wasteful number, since it uses less digits than its factorization.

21317972838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35178279.

The product of its digits is 1016064, while the sum is 51.

The spelling of 21317972838 in words is "twenty-one billion, three hundred seventeen million, nine hundred seventy-two thousand, eight hundred thirty-eight".