21565270746 has 72 divisors (see below), whose sum is σ = 49767211260. Its totient is φ = 6747549696.

The previous prime is 21565270721. The next prime is 21565270747. The reversal of 21565270746 is 64707256512.

21565270746 is a `hidden beast` number, since 2 + 1 + 56 + 527 + 0 + 74 + 6 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 8228485521 + 13336785225 = 90711^2 + 115485^2 .

It is not an unprimeable number, because it can be changed into a prime (21565270747) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2018250 + ... + 2028906.

Almost surely, 2^21565270746 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21565270746, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24883605630).

21565270746 is an abundant number, since it is smaller than the sum of its proper divisors (28201940514).

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

21565270746 is a wasteful number, since it uses less digits than its factorization.

21565270746 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11088 (or 11068 counting only the distinct ones).

The product of its (nonzero) digits is 705600, while the sum is 45.

The spelling of 21565270746 in words is "twenty-one billion, five hundred sixty-five million, two hundred seventy thousand, seven hundred forty-six".