77939691 has 16 divisors (see below), whose sum is σ = 110893440. Its totient is φ = 48548160.

The previous prime is 77939681. The next prime is 77939699. The reversal of 77939691 is 19693977.

It is not a de Polignac number, because 77939691 - 2¹⁰ = 77938667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77939699) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5205 + ... + 13526.

It is an arithmetic number, because the mean of its divisors is an integer number (6930840).

Almost surely, 2^77939691 is an apocalyptic number.

77939691 is a deficient number, since it is larger than the sum of its proper divisors (32953749).

77939691 is a wasteful number, since it uses less digits than its factorization.

77939691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18826.

The product of its digits is 642978, while the sum is 51.

The square root of 77939691 is about 8828.3458813076. The cubic root of 77939691 is about 427.1557202155.

It can be divided in two parts, 779 and 39691, that added together give a triangular number (40470 = T₂₈₄).

The spelling of 77939691 in words is "seventy-seven million, nine hundred thirty-nine thousand, six hundred ninety-one".