565261881921 has 27 divisors (see below), whose sum is σ = 897502932417. Its totient is φ = 342567921960.

The previous prime is 565261881911. The next prime is 565261881971. The reversal of 565261881921 is 129188162565.

The square root of 565261881921 is 751839.

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

565261881921 is a `hidden beast` number, since 5 + 6 + 5 + 2 + 618 + 8 + 19 + 2 + 1 = 666.

It is not a de Polignac number, because 565261881921 - 2⁵ = 565261881889 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (565261881911) 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, 24799296 + ... + 24822078.

Almost surely, 2^565261881921 is an apocalyptic number.

565261881921 is the 751839-th square number.

565261881921 is the 375920-th centered octagonal number.

It is an amenable number.

565261881921 is a deficient number, since it is larger than the sum of its proper divisors (332241050496).

565261881921 is an frugal number, since it uses more digits than its factorization.

565261881921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45594 (or 22797 counting only the distinct ones).

The product of its digits is 2073600, while the sum is 54.

The spelling of 565261881921 in words is "five hundred sixty-five billion, two hundred sixty-one million, eight hundred eighty-one thousand, nine hundred twenty-one".