77561831 has 2 divisors, whose sum is σ = 77561832. Its totient is φ = 77561830.

The previous prime is 77561807. The next prime is 77561851. The reversal of 77561831 is 13816577.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 77561831 - 2⁶ = 77561767 is a prime.

It is a super-2 number, since 2×77561831² = 12031675256145122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77561851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38780915 + 38780916.

It is an arithmetic number, because the mean of its divisors is an integer number (38780916).

Almost surely, 2^77561831 is an apocalyptic number.

77561831 is a deficient number, since it is larger than the sum of its proper divisors (1).

77561831 is an equidigital number, since it uses as much as digits as its factorization.

77561831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 38.

The square root of 77561831 is about 8806.9194954876. The cubic root of 77561831 is about 426.4643027039.

The spelling of 77561831 in words is "seventy-seven million, five hundred sixty-one thousand, eight hundred thirty-one".