138993390 has 96 divisors (see below), whose sum is σ = 371329920. Its totient is φ = 36062208.

The previous prime is 138993383. The next prime is 138993409. The reversal of 138993390 is 93399831.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 803344 + ... + 803516.

It is an arithmetic number, because the mean of its divisors is an integer number (3868020).

Almost surely, 2^138993390 is an apocalyptic number.

138993390 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 138993390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (185664960).

138993390 is an abundant number, since it is smaller than the sum of its proper divisors (232336530).

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

138993390 is a wasteful number, since it uses less digits than its factorization.

138993390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 378 (or 375 counting only the distinct ones).

The product of its (nonzero) digits is 157464, while the sum is 45.

The square root of 138993390 is about 11789.5457927776. The cubic root of 138993390 is about 518.0019354638.

The spelling of 138993390 in words is "one hundred thirty-eight million, nine hundred ninety-three thousand, three hundred ninety".