138409398 has 56 divisors (see below), whose sum is σ = 316751400. Its totient is φ = 45326304.

The previous prime is 138409379. The next prime is 138409409. The reversal of 138409398 is 893904831.

It is a super-2 number, since 2×138409398² = 38314322909444808, which contains 22 as substring.

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, 85218 + ... + 86826.

It is an arithmetic number, because the mean of its divisors is an integer number (5656275).

Almost surely, 2^138409398 is an apocalyptic number.

138409398 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 138409398, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158375700).

138409398 is an abundant number, since it is smaller than the sum of its proper divisors (178342002).

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

138409398 is an equidigital number, since it uses as much as digits as its factorization.

138409398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1688 (or 1673 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 138409398 is about 11764.7523560847. The cubic root of 138409398 is about 517.2754413238.

The spelling of 138409398 in words is "one hundred thirty-eight million, four hundred nine thousand, three hundred ninety-eight".