77768813 has 4 divisors (see below), whose sum is σ = 77792988. Its totient is φ = 77744640.

The previous prime is 77768809. The next prime is 77768849. The reversal of 77768813 is 31886777.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31886777 = 13 ⋅2452829.

It can be written as a sum of positive squares in 2 ways, for example, as 51523684 + 26245129 = 7178^2 + 5123^2 .

It is a cyclic number.

It is not a de Polignac number, because 77768813 - 2² = 77768809 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77768893) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6356 + ... + 13997.

It is an arithmetic number, because the mean of its divisors is an integer number (19448247).

Almost surely, 2^77768813 is an apocalyptic number.

It is an amenable number.

77768813 is a deficient number, since it is larger than the sum of its proper divisors (24175).

77768813 is a wasteful number, since it uses less digits than its factorization.

77768813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24174.

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

The square root of 77768813 is about 8818.6627671093. The cubic root of 77768813 is about 426.8433208786.

The spelling of 77768813 in words is "seventy-seven million, seven hundred sixty-eight thousand, eight hundred thirteen".