138781944 has 128 divisors (see below), whose sum is σ = 443520000. Its totient is φ = 39388032.

The previous prime is 138781943. The next prime is 138781957. The reversal of 138781944 is 449187831.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 138781944.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138781943) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 397482 + ... + 397830.

It is an arithmetic number, because the mean of its divisors is an integer number (3465000).

Almost surely, 2^138781944 is an apocalyptic number.

138781944 is a gapful number since it is divisible by the number (14) 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 138781944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (221760000).

138781944 is an abundant number, since it is smaller than the sum of its proper divisors (304738056).

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

138781944 is a wasteful number, since it uses less digits than its factorization.

138781944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634 (or 624 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 138781944 is about 11780.5748586391. The cubic root of 138781944 is about 517.7391291405.

The spelling of 138781944 in words is "one hundred thirty-eight million, seven hundred eighty-one thousand, nine hundred forty-four".