138658878 has 20 divisors (see below), whose sum is σ = 310698960. Its totient is φ = 46219572.

The previous prime is 138658859. The next prime is 138658937. The reversal of 138658878 is 878856831.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 427798 + ... + 428121.

It is an arithmetic number, because the mean of its divisors is an integer number (15534948).

Almost surely, 2^138658878 is an apocalyptic number.

138658878 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

138658878 is an abundant number, since it is smaller than the sum of its proper divisors (172040082).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

138658878 is an equidigital number, since it uses as much as digits as its factorization.

138658878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 855933 (or 855924 counting only the distinct ones).

The product of its digits is 2580480, while the sum is 54.

The square root of 138658878 is about 11775.3504406451. The cubic root of 138658878 is about 517.5860474434.

The spelling of 138658878 in words is "one hundred thirty-eight million, six hundred fifty-eight thousand, eight hundred seventy-eight".