77865891 has 4 divisors (see below), whose sum is σ = 103821192. Its totient is φ = 51910592.

The previous prime is 77865889. The next prime is 77865919. The reversal of 77865891 is 19856877.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19856877 = 3 ⋅6618959.

It is a cyclic number.

It is not a de Polignac number, because 77865891 - 2¹ = 77865889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77865811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12977646 + ... + 12977651.

It is an arithmetic number, because the mean of its divisors is an integer number (25955298).

Almost surely, 2^77865891 is an apocalyptic number.

77865891 is a deficient number, since it is larger than the sum of its proper divisors (25955301).

77865891 is a wasteful number, since it uses less digits than its factorization.

77865891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25955300.

The product of its digits is 846720, while the sum is 51.

The square root of 77865891 is about 8824.1651729781. The cubic root of 77865891 is about 427.0208550529.

The spelling of 77865891 in words is "seventy-seven million, eight hundred sixty-five thousand, eight hundred ninety-one".