21238398756 has 81 divisors (see below), whose sum is σ = 54432164059. Its totient is φ = 6982407408.

The previous prime is 21238398751. The next prime is 21238398757. The reversal of 21238398756 is 65789383212.

The square root of 21238398756 is 145734.

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

21238398756 is a `hidden beast` number, since 212 + 38 + 398 + 7 + 5 + 6 = 666.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21238398751) 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, 93561115 + ... + 93561341.

Almost surely, 2^21238398756 is an apocalyptic number.

21238398756 is the 145734-th square number.

It is an amenable number.

21238398756 is an abundant number, since it is smaller than the sum of its proper divisors (33193765303).

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

21238398756 is a wasteful number, since it uses less digits than its factorization.

21238398756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678 (or 339 counting only the distinct ones).

The product of its digits is 4354560, while the sum is 54.

The spelling of 21238398756 in words is "twenty-one billion, two hundred thirty-eight million, three hundred ninety-eight thousand, seven hundred fifty-six".