77981717 has 12 divisors (see below), whose sum is σ = 85949388. Its totient is φ = 70699200.

The previous prime is 77981699. The next prime is 77981723. The reversal of 77981717 is 71718977.

It can be written as a sum of positive squares in 2 ways, for example, as 40844881 + 37136836 = 6391^2 + 6094^2 .

It is not a de Polignac number, because 77981717 - 2¹⁴ = 77965333 is a prime.

It is a super-2 number, since 2×77981717² = 12162296372536178, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77981777) 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, 62423 + ... + 63659.

It is an arithmetic number, because the mean of its divisors is an integer number (7162449).

Almost surely, 2^77981717 is an apocalyptic number.

It is an amenable number.

77981717 is a deficient number, since it is larger than the sum of its proper divisors (7967671).

77981717 is a wasteful number, since it uses less digits than its factorization.

77981717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1780 (or 1769 counting only the distinct ones).

The product of its digits is 172872, while the sum is 47.

The square root of 77981717 is about 8830.7257346155. The cubic root of 77981717 is about 427.2324822198.

The spelling of 77981717 in words is "seventy-seven million, nine hundred eighty-one thousand, seven hundred seventeen".