21720821032 has 8 divisors (see below), whose sum is σ = 40726539450. Its totient is φ = 10860410512.

The previous prime is 21720821027. The next prime is 21720821123. The reversal of 21720821032 is 23012802712.

It can be written as a sum of positive squares in only one way, i.e., 20228235076 + 1492585956 = 142226^2 + 38634^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1357551307 + ... + 1357551322.

Almost surely, 2^21720821032 is an apocalyptic number.

It is an amenable number.

21720821032 is a deficient number, since it is larger than the sum of its proper divisors (19005718418).

21720821032 is a wasteful number, since it uses less digits than its factorization.

21720821032 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2715102635 (or 2715102631 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The spelling of 21720821032 in words is "twenty-one billion, seven hundred twenty million, eight hundred twenty-one thousand, thirty-two".