138188920 has 64 divisors (see below), whose sum is σ = 332579520. Its totient is φ = 51492864.

The previous prime is 138188909. The next prime is 138188923. The reversal of 138188920 is 29881831.

It is a super-2 number, since 2×138188920² = 38192355221532800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138188923) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69054 + ... + 71026.

It is an arithmetic number, because the mean of its divisors is an integer number (5196555).

Almost surely, 2^138188920 is an apocalyptic number.

138188920 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 138188920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (166289760).

138188920 is an abundant number, since it is smaller than the sum of its proper divisors (194390600).

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

138188920 is a wasteful number, since it uses less digits than its factorization.

138188920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2104 (or 2100 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 40.

The square root of 138188920 is about 11755.3783435498. The cubic root of 138188920 is about 517.0006322737. Note that the first 3 decimals are identical.

The spelling of 138188920 in words is "one hundred thirty-eight million, one hundred eighty-eight thousand, nine hundred twenty".