77128191 has 12 divisors (see below), whose sum is σ = 127322832. Its totient is φ = 44073216.

The previous prime is 77128159. The next prime is 77128193. The reversal of 77128191 is 19182177.

It is not a de Polignac number, because 77128191 - 2⁵ = 77128159 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77128193) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 612066 + ... + 612191.

It is an arithmetic number, because the mean of its divisors is an integer number (10610236).

Almost surely, 2^77128191 is an apocalyptic number.

77128191 is a deficient number, since it is larger than the sum of its proper divisors (50194641).

77128191 is a wasteful number, since it uses less digits than its factorization.

77128191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1224270 (or 1224267 counting only the distinct ones).

The product of its digits is 7056, while the sum is 36.

The square root of 77128191 is about 8782.2657099407. The cubic root of 77128191 is about 425.6680446417.

The spelling of 77128191 in words is "seventy-seven million, one hundred twenty-eight thousand, one hundred ninety-one".