77561631 has 80 divisors (see below), whose sum is σ = 141134400. Its totient is φ = 41513472.

The previous prime is 77561623. The next prime is 77561639. The reversal of 77561631 is 13616577.

77561631 is a `hidden beast` number, since 7 + 7 + 5 + 616 + 31 = 666.

It is an interprime number because it is at equal distance from previous prime (77561623) and next prime (77561639).

It is not a de Polignac number, because 77561631 - 2³ = 77561623 is a prime.

It is a super-2 number, since 2×77561631² = 12031613206760322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77561639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 871435 + ... + 871523.

It is an arithmetic number, because the mean of its divisors is an integer number (1764180).

Almost surely, 2^77561631 is an apocalyptic number.

77561631 is a deficient number, since it is larger than the sum of its proper divisors (63572769).

77561631 is a wasteful number, since it uses less digits than its factorization.

77561631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190 (or 181 counting only the distinct ones).

The product of its digits is 26460, while the sum is 36.

The square root of 77561631 is about 8806.9081407722. The cubic root of 77561631 is about 426.4639361451.

The spelling of 77561631 in words is "seventy-seven million, five hundred sixty-one thousand, six hundred thirty-one".