77685409 has 2 divisors, whose sum is σ = 77685410. Its totient is φ = 77685408.

The previous prime is 77685401. The next prime is 77685449. The reversal of 77685409 is 90458677.

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., 53949025 + 23736384 = 7345^2 + 4872^2 .

It is a cyclic number.

It is not a de Polignac number, because 77685409 - 2³ = 77685401 is a prime.

It is not a weakly prime, because it can be changed into another prime (77685401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38842704 + 38842705.

It is an arithmetic number, because the mean of its divisors is an integer number (38842705).

Almost surely, 2^77685409 is an apocalyptic number.

It is an amenable number.

77685409 is a deficient number, since it is larger than the sum of its proper divisors (1).

77685409 is an equidigital number, since it uses as much as digits as its factorization.

77685409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 423360, while the sum is 46.

The square root of 77685409 is about 8813.9326636865. The cubic root of 77685409 is about 426.6906753932.

The spelling of 77685409 in words is "seventy-seven million, six hundred eighty-five thousand, four hundred nine".