21328972722 has 54 divisors (see below), whose sum is σ = 47901623133. Its totient is φ = 6858713904.

The previous prime is 21328972711. The next prime is 21328972729. The reversal of 21328972722 is 22727982312.

It can be written as a sum of positive squares in 2 ways, for example, as 21316292001 + 12680721 = 146001^2 + 3561^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=103269.

It is not an unprimeable number, because it can be changed into a prime (21328972729) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 17968213 + ... + 17969399.

Almost surely, 2^21328972722 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21328972722

21328972722 is an abundant number, since it is smaller than the sum of its proper divisors (26572650411).

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

21328972722 is an equidigital number, since it uses as much as digits as its factorization.

21328972722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2440 (or 1221 counting only the distinct ones).

The product of its digits is 338688, while the sum is 45.

The spelling of 21328972722 in words is "twenty-one billion, three hundred twenty-eight million, nine hundred seventy-two thousand, seven hundred twenty-two".