138909798 has 24 divisors (see below), whose sum is σ = 316812600. Its totient is φ = 43866144.

The previous prime is 138909781. The next prime is 138909809. The reversal of 138909798 is 897909831.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 202743 + ... + 203426.

It is an arithmetic number, because the mean of its divisors is an integer number (13200525).

Almost surely, 2^138909798 is an apocalyptic number.

138909798 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

138909798 is an abundant number, since it is smaller than the sum of its proper divisors (177902802).

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

138909798 is a wasteful number, since it uses less digits than its factorization.

138909798 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406196 (or 406193 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 54.

The square root of 138909798 is about 11786.0000848464. Note that the first 4 decimals coincide. The cubic root of 138909798 is about 517.8980708095.

The spelling of 138909798 in words is "one hundred thirty-eight million, nine hundred nine thousand, seven hundred ninety-eight".