21639901700 has 18 divisors (see below), whose sum is σ = 46958586906. Its totient is φ = 8655960640.

The previous prime is 21639901697. The next prime is 21639901709. The reversal of 21639901700 is 710993612.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 1248632896 + 20391268804 = 35336^2 + 142798^2 .

It is not an unprimeable number, because it can be changed into a prime (21639901709) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 108199409 + ... + 108199608.

Almost surely, 2^21639901700 is an apocalyptic number.

21639901700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21639901700 is an abundant number, since it is smaller than the sum of its proper divisors (25318685206).

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

21639901700 is a wasteful number, since it uses less digits than its factorization.

21639901700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216399031 (or 216399024 counting only the distinct ones).

The product of its (nonzero) digits is 20412, while the sum is 38.

The spelling of 21639901700 in words is "twenty-one billion, six hundred thirty-nine million, nine hundred one thousand, seven hundred".