21397253284 has 81 divisors (see below), whose sum is σ = 42231978243. Its totient is φ = 9478814400.

The previous prime is 21397253281. The next prime is 21397253357. The reversal of 21397253284 is 48235279312.

The square root of 21397253284 is 146278.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 3269323684 + 18127929600 = 57178^2 + 134640^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21397253281) 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, 196305022 + ... + 196305130.

Almost surely, 2^21397253284 is an apocalyptic number.

21397253284 is the 146278-th square number.

It is an amenable number.

21397253284 is a deficient number, since it is larger than the sum of its proper divisors (20834724959).

21397253284 is a wasteful number, since it uses less digits than its factorization.

21397253284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366 (or 183 counting only the distinct ones).

The product of its digits is 725760, while the sum is 46.

The spelling of 21397253284 in words is "twenty-one billion, three hundred ninety-seven million, two hundred fifty-three thousand, two hundred eighty-four".