77979791 has 4 divisors (see below), whose sum is σ = 78005784. Its totient is φ = 77953800.

The previous prime is 77979779. The next prime is 77979851. The reversal of 77979791 is 19797977.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19797977 = 61 ⋅324557.

It is a cyclic number.

It is not a de Polignac number, because 77979791 - 2¹⁴ = 77963407 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 (77979701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7805 + ... + 14726.

It is an arithmetic number, because the mean of its divisors is an integer number (19501446).

Almost surely, 2^77979791 is an apocalyptic number.

77979791 is a deficient number, since it is larger than the sum of its proper divisors (25993).

77979791 is a wasteful number, since it uses less digits than its factorization.

77979791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25992.

The product of its digits is 1750329, while the sum is 56.

The square root of 77979791 is about 8830.6166828823. The cubic root of 77979791 is about 427.2289649144.

The spelling of 77979791 in words is "seventy-seven million, nine hundred seventy-nine thousand, seven hundred ninety-one".