78288139 has 4 divisors (see below), whose sum is σ = 80987760. Its totient is φ = 75588520.

The previous prime is 78288121. The next prime is 78288143. The reversal of 78288139 is 93188287.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93188287 = 2719 ⋅34273.

It is a cyclic number.

It is not a de Polignac number, because 78288139 - 2⁵ = 78288107 is a prime.

It is a super-2 number, since 2×78288139² = 12258065416166642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78288109) 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, 1349767 + ... + 1349824.

It is an arithmetic number, because the mean of its divisors is an integer number (20246940).

Almost surely, 2^78288139 is an apocalyptic number.

78288139 is a deficient number, since it is larger than the sum of its proper divisors (2699621).

78288139 is a wasteful number, since it uses less digits than its factorization.

78288139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2699620.

The product of its digits is 193536, while the sum is 46.

The square root of 78288139 is about 8848.0584876005. The cubic root of 78288139 is about 427.7913411390.

The spelling of 78288139 in words is "seventy-eight million, two hundred eighty-eight thousand, one hundred thirty-nine".