78931577 has 4 divisors (see below), whose sum is σ = 79027620. Its totient is φ = 78835536.

The previous prime is 78931571. The next prime is 78931579. The reversal of 78931577 is 77513987.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 77513987 = 829 ⋅93503.

It can be written as a sum of positive squares in 2 ways, for example, as 29637136 + 49294441 = 5444^2 + 7021^2 .

It is a cyclic number.

It is not a de Polignac number, because 78931577 - 2¹⁶ = 78866041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78931571) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46778 + ... + 48435.

It is an arithmetic number, because the mean of its divisors is an integer number (19756905).

Almost surely, 2^78931577 is an apocalyptic number.

It is an amenable number.

78931577 is a deficient number, since it is larger than the sum of its proper divisors (96043).

78931577 is an equidigital number, since it uses as much as digits as its factorization.

78931577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96042.

The product of its digits is 370440, while the sum is 47.

The square root of 78931577 is about 8884.3444890436. The cubic root of 78931577 is about 428.9601283664.

The spelling of 78931577 in words is "seventy-eight million, nine hundred thirty-one thousand, five hundred seventy-seven".