21108720732 has 24 divisors (see below), whose sum is σ = 53731289472. Its totient is φ = 6396582000.

The previous prime is 21108720713. The next prime is 21108720749. The reversal of 21108720732 is 23702780112.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a junction number, because it is equal to n+sod(n) for n = 21108720693 and 21108720702.

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, 79957144 + ... + 79957407.

It is an arithmetic number, because the mean of its divisors is an integer number (2238803728).

Almost surely, 2^21108720732 is an apocalyptic number.

21108720732 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21108720732 is an abundant number, since it is smaller than the sum of its proper divisors (32622568740).

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

21108720732 is a wasteful number, since it uses less digits than its factorization.

21108720732 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159914569 (or 159914567 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 33.

The spelling of 21108720732 in words is "twenty-one billion, one hundred eight million, seven hundred twenty thousand, seven hundred thirty-two".