77711991 has 24 divisors (see below), whose sum is σ = 120887424. Its totient is φ = 44276400.

The previous prime is 77711989. The next prime is 77712001. The reversal of 77711991 is 19911777.

It is not a de Polignac number, because 77711991 - 2¹ = 77711989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77711911) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 73416 + ... + 74466.

It is an arithmetic number, because the mean of its divisors is an integer number (5036976).

Almost surely, 2^77711991 is an apocalyptic number.

77711991 is a deficient number, since it is larger than the sum of its proper divisors (43175433).

77711991 is a wasteful number, since it uses less digits than its factorization.

77711991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1571 (or 1564 counting only the distinct ones).

The product of its digits is 27783, while the sum is 42.

The square root of 77711991 is about 8815.4404881435. The cubic root of 77711991 is about 426.7393374618.

The spelling of 77711991 in words is "seventy-seven million, seven hundred eleven thousand, nine hundred ninety-one".