138899981 has 8 divisors (see below), whose sum is σ = 151660128. Its totient is φ = 126162000.

The previous prime is 138899963. The next prime is 138900007. The reversal of 138899981 is 189998831.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 138899981 - 2²² = 134705677 is a prime.

It is a super-2 number, since 2×138899981² = 38586409443600722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138899951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9311 + ... + 19091.

It is an arithmetic number, because the mean of its divisors is an integer number (18957516).

Almost surely, 2^138899981 is an apocalyptic number.

138899981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

138899981 is a deficient number, since it is larger than the sum of its proper divisors (12760147).

138899981 is a wasteful number, since it uses less digits than its factorization.

138899981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11083.

The product of its digits is 1119744, while the sum is 56.

The square root of 138899981 is about 11785.5836087994. The cubic root of 138899981 is about 517.8858702659.

The spelling of 138899981 in words is "one hundred thirty-eight million, eight hundred ninety-nine thousand, nine hundred eighty-one".