21637149720 has 64 divisors (see below), whose sum is σ = 67733694720. Its totient is φ = 5519040384.

The previous prime is 21637149679. The next prime is 21637149739. The reversal of 21637149720 is 2794173612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3917014 + ... + 3922533.

It is an arithmetic number, because the mean of its divisors is an integer number (1058338980).

Almost surely, 2^21637149720 is an apocalyptic number.

21637149720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21637149720 is an abundant number, since it is smaller than the sum of its proper divisors (46096545000).

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

21637149720 is a wasteful number, since it uses less digits than its factorization.

21637149720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7839584 (or 7839580 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 42.

The spelling of 21637149720 in words is "twenty-one billion, six hundred thirty-seven million, one hundred forty-nine thousand, seven hundred twenty".