77131609 has 2 divisors, whose sum is σ = 77131610. Its totient is φ = 77131608.

The previous prime is 77131597. The next prime is 77131661. The reversal of 77131609 is 90613177.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73051209 + 4080400 = 8547^2 + 2020^2 .

It is an emirp because it is prime and its reverse (90613177) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77131609 - 2⁵ = 77131577 is a prime.

It is not a weakly prime, because it can be changed into another prime (77137609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38565804 + 38565805.

It is an arithmetic number, because the mean of its divisors is an integer number (38565805).

Almost surely, 2^77131609 is an apocalyptic number.

It is an amenable number.

77131609 is a deficient number, since it is larger than the sum of its proper divisors (1).

77131609 is an equidigital number, since it uses as much as digits as its factorization.

77131609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7938, while the sum is 34.

The square root of 77131609 is about 8782.4603044933. The cubic root of 77131609 is about 425.6743324934.

The spelling of 77131609 in words is "seventy-seven million, one hundred thirty-one thousand, six hundred nine".