77678813 has 2 divisors, whose sum is σ = 77678814. Its totient is φ = 77678812.

The previous prime is 77678801. The next prime is 77678819. The reversal of 77678813 is 31887677.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73239364 + 4439449 = 8558^2 + 2107^2 .

It is a cyclic number.

It is not a de Polignac number, because 77678813 - 2²⁴ = 60901597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77678819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38839406 + 38839407.

It is an arithmetic number, because the mean of its divisors is an integer number (38839407).

Almost surely, 2^77678813 is an apocalyptic number.

It is an amenable number.

77678813 is a deficient number, since it is larger than the sum of its proper divisors (1).

77678813 is an equidigital number, since it uses as much as digits as its factorization.

77678813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 395136, while the sum is 47.

The square root of 77678813 is about 8813.5584754400. The cubic root of 77678813 is about 426.6785987738.

The spelling of 77678813 in words is "seventy-seven million, six hundred seventy-eight thousand, eight hundred thirteen".