77109891 has 4 divisors (see below), whose sum is σ = 102813192. Its totient is φ = 51406592.

The previous prime is 77109881. The next prime is 77109931. The reversal of 77109891 is 19890177.

It is a happy number.

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 77109891 - 2⁹ = 77109379 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77109821) 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, 12851646 + ... + 12851651.

It is an arithmetic number, because the mean of its divisors is an integer number (25703298).

Almost surely, 2^77109891 is an apocalyptic number.

77109891 is a deficient number, since it is larger than the sum of its proper divisors (25703301).

77109891 is a wasteful number, since it uses less digits than its factorization.

77109891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25703300.

The product of its (nonzero) digits is 31752, while the sum is 42.

The square root of 77109891 is about 8781.2237757616. The cubic root of 77109891 is about 425.6343762718.

The spelling of 77109891 in words is "seventy-seven million, one hundred nine thousand, eight hundred ninety-one".