78521139 has 24 divisors (see below), whose sum is σ = 116983152. Its totient is φ = 50722560.

The previous prime is 78521111. The next prime is 78521189. The reversal of 78521139 is 93112587.

It is not a de Polignac number, because 78521139 - 2¹⁶ = 78455603 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78521189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52279 + ... + 53759.

It is an arithmetic number, because the mean of its divisors is an integer number (4874298).

Almost surely, 2^78521139 is an apocalyptic number.

78521139 is a deficient number, since it is larger than the sum of its proper divisors (38462013).

78521139 is a wasteful number, since it uses less digits than its factorization.

78521139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1667 (or 1664 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 78521139 is about 8861.2154358192. The cubic root of 78521139 is about 428.2153162256.

The spelling of 78521139 in words is "seventy-eight million, five hundred twenty-one thousand, one hundred thirty-nine".