138978585 has 40 divisors (see below), whose sum is σ = 257744520. Its totient is φ = 71559936.

The previous prime is 138978563. The next prime is 138978589. The reversal of 138978585 is 585879831.

It can be written as a sum of positive squares in 4 ways, for example, as 45198729 + 93779856 = 6723^2 + 9684^2 .

It is not a de Polignac number, because 138978585 - 2⁷ = 138978457 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (138978589) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 5829 + ... + 17661.

It is an arithmetic number, because the mean of its divisors is an integer number (6443613).

Almost surely, 2^138978585 is an apocalyptic number.

138978585 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

138978585 is a deficient number, since it is larger than the sum of its proper divisors (118765935).

138978585 is a wasteful number, since it uses less digits than its factorization.

138978585 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11879 (or 11870 counting only the distinct ones).

The product of its digits is 2419200, while the sum is 54.

The square root of 138978585 is about 11788.9178892721. The cubic root of 138978585 is about 517.9835430041.

The spelling of 138978585 in words is "one hundred thirty-eight million, nine hundred seventy-eight thousand, five hundred eighty-five".