77778979 has 4 divisors (see below), whose sum is σ = 78338680. Its totient is φ = 77219280.

The previous prime is 77778971. The next prime is 77778983. The reversal of 77778979 is 97987777.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 77778979 - 2³ = 77778971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77778971) 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, 279642 + ... + 279919.

It is an arithmetic number, because the mean of its divisors is an integer number (19584670).

Almost surely, 2^77778979 is an apocalyptic number.

77778979 is a deficient number, since it is larger than the sum of its proper divisors (559701).

77778979 is a wasteful number, since it uses less digits than its factorization.

77778979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 559700.

The product of its digits is 10890936, while the sum is 61.

The square root of 77778979 is about 8819.2391395176. The cubic root of 77778979 is about 426.8619191657.

The spelling of 77778979 in words is "seventy-seven million, seven hundred seventy-eight thousand, nine hundred seventy-nine".