561164293881 has 9 divisors (see below), whose sum is σ = 810573892869. Its totient is φ = 374108031036.

The previous prime is 561164293873. The next prime is 561164293883. The reversal of 561164293881 is 188392461165.

It is a happy number.

The square root of 561164293881 is 749109.

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

561164293881 is a `hidden beast` number, since 561 + 1 + 6 + 42 + 9 + 38 + 8 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 561164293881 - 2³ = 561164293873 is a prime.

It is a super-2 number, since 2×561164293881² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (561164293883) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2122476 + ... + 2372178.

Almost surely, 2^561164293881 is an apocalyptic number.

561164293881 is the 749109-th square number.

561164293881 is the 374555-th centered octagonal number.

It is an amenable number.

561164293881 is a deficient number, since it is larger than the sum of its proper divisors (249409598988).

561164293881 is an frugal number, since it uses more digits than its factorization.

561164293881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 499412 (or 249706 counting only the distinct ones).

The product of its digits is 2488320, while the sum is 54.

The spelling of 561164293881 in words is "five hundred sixty-one billion, one hundred sixty-four million, two hundred ninety-three thousand, eight hundred eighty-one".