138978720 has 192 divisors, whose sum is σ = 496419840. Its totient is φ = 36301824.

The previous prime is 138978713. The next prime is 138978731. The reversal of 138978720 is 27879831.

It is a super-2 number, since 2×138978720² = 38630169225676800, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 228657 + ... + 229263.

It is an arithmetic number, because the mean of its divisors is an integer number (2585520).

Almost surely, 2^138978720 is an apocalyptic number.

138978720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138978720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (248209920).

138978720 is an abundant number, since it is smaller than the sum of its proper divisors (357441120).

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

138978720 is a wasteful number, since it uses less digits than its factorization.

138978720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 684 (or 670 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 45.

The square root of 138978720 is about 11788.9236149871. The cubic root of 138978720 is about 517.9837107224.

The spelling of 138978720 in words is "one hundred thirty-eight million, nine hundred seventy-eight thousand, seven hundred twenty".