78208639 has 4 divisors (see below), whose sum is σ = 80322424. Its totient is φ = 76094856.

The previous prime is 78208609. The next prime is 78208667. The reversal of 78208639 is 93680287.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 78208639 - 2²³ = 69820031 is a prime.

It is a super-2 number, since 2×78208639² = 12233182428464642, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 78208595 and 78208604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78208609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1056837 + ... + 1056910.

It is an arithmetic number, because the mean of its divisors is an integer number (20080606).

Almost surely, 2^78208639 is an apocalyptic number.

78208639 is a deficient number, since it is larger than the sum of its proper divisors (2113785).

78208639 is a wasteful number, since it uses less digits than its factorization.

78208639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2113784.

The product of its (nonzero) digits is 145152, while the sum is 43.

The square root of 78208639 is about 8843.5648355174. The cubic root of 78208639 is about 427.6464876507.

The spelling of 78208639 in words is "seventy-eight million, two hundred eight thousand, six hundred thirty-nine".