138999888 has 140 divisors (see below), whose sum is σ = 428145588. Its totient is φ = 43545600.

The previous prime is 138999869. The next prime is 138999899. The reversal of 138999888 is 888999831.

It can be written as a sum of positive squares in 2 ways, for example, as 114318864 + 24681024 = 10692^2 + 4968^2 .

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 197938 + ... + 198638.

Almost surely, 2^138999888 is an apocalyptic number.

138999888 is a gapful number since it is divisible by the number (18) 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 138999888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (214072794).

138999888 is an abundant number, since it is smaller than the sum of its proper divisors (289145700).

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

138999888 is an equidigital number, since it uses as much as digits as its factorization.

138999888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 744 (or 723 counting only the distinct ones).

The product of its digits is 8957952, while the sum is 63.

The square root of 138999888 is about 11789.8213726926. The cubic root of 138999888 is about 518.0100076082.

The spelling of 138999888 in words is "one hundred thirty-eight million, nine hundred ninety-nine thousand, eight hundred eighty-eight".