77131661 has 2 divisors, whose sum is σ = 77131662. Its totient is φ = 77131660.

The previous prime is 77131609. The next prime is 77131667. The reversal of 77131661 is 16613177.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76650025 + 481636 = 8755^2 + 694^2 .

It is a cyclic number.

It is not a de Polignac number, because 77131661 - 2⁶ = 77131597 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77131667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38565830 + 38565831.

It is an arithmetic number, because the mean of its divisors is an integer number (38565831).

Almost surely, 2^77131661 is an apocalyptic number.

It is an amenable number.

77131661 is a deficient number, since it is larger than the sum of its proper divisors (1).

77131661 is an equidigital number, since it uses as much as digits as its factorization.

77131661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5292, while the sum is 32.

The square root of 77131661 is about 8782.4632649388. The cubic root of 77131661 is about 425.6744281527.

The spelling of 77131661 in words is "seventy-seven million, one hundred thirty-one thousand, six hundred sixty-one".