78139791 has 6 divisors (see below), whose sum is σ = 112868600. Its totient is φ = 52093188.

The previous prime is 78139783. The next prime is 78139793. The reversal of 78139791 is 19793187.

It is not a de Polignac number, because 78139791 - 2³ = 78139783 is a prime.

It is a super-2 number, since 2×78139791² = 12211653875047362, 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 (78139793) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4341091 + ... + 4341108.

Almost surely, 2^78139791 is an apocalyptic number.

78139791 is a deficient number, since it is larger than the sum of its proper divisors (34728809).

78139791 is a wasteful number, since it uses less digits than its factorization.

78139791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8682205 (or 8682202 counting only the distinct ones).

The product of its digits is 95256, while the sum is 45.

The square root of 78139791 is about 8839.6714305454. The cubic root of 78139791 is about 427.5209633713.

The spelling of 78139791 in words is "seventy-eight million, one hundred thirty-nine thousand, seven hundred ninety-one".