21002120992 has 24 divisors (see below), whose sum is σ = 41757317532. Its totient is φ = 10397088000.

The previous prime is 21002120987. The next prime is 21002120999. The reversal of 21002120992 is 29902120012.

It can be written as a sum of positive squares in 2 ways, for example, as 19487043216 + 1515077776 = 139596^2 + 38924^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21002120992.

It is not an unprimeable number, because it can be changed into a prime (21002120999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3245859 + ... + 3252322.

Almost surely, 2^21002120992 is an apocalyptic number.

It is an amenable number.

21002120992 is a deficient number, since it is larger than the sum of its proper divisors (20755196540).

21002120992 is a wasteful number, since it uses less digits than its factorization.

21002120992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6498292 (or 6498284 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 28.

The spelling of 21002120992 in words is "twenty-one billion, two million, one hundred twenty thousand, nine hundred ninety-two".