77942991 has 16 divisors (see below), whose sum is σ = 118951424. Its totient is φ = 44470944.

The previous prime is 77942989. The next prime is 77943001. The reversal of 77942991 is 19924977.

It is a happy number.

It is not a de Polignac number, because 77942991 - 2¹ = 77942989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77942991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77942911) 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 15 ways as a sum of consecutive naturals, for example, 13446 + ... + 18348.

It is an arithmetic number, because the mean of its divisors is an integer number (7434464).

Almost surely, 2^77942991 is an apocalyptic number.

77942991 is a deficient number, since it is larger than the sum of its proper divisors (41008433).

77942991 is a wasteful number, since it uses less digits than its factorization.

77942991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5670.

The product of its digits is 285768, while the sum is 48.

The square root of 77942991 is about 8828.5327773079. The cubic root of 77942991 is about 427.1617487827.

The spelling of 77942991 in words is "seventy-seven million, nine hundred forty-two thousand, nine hundred ninety-one".