138928644 has 72 divisors (see below), whose sum is σ = 358918560. Its totient is φ = 45302400.

The previous prime is 138928619. The next prime is 138928667. The reversal of 138928644 is 446829831.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 138928644.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 419559 + ... + 419889.

It is an arithmetic number, because the mean of its divisors is an integer number (4984980).

Almost surely, 2^138928644 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138928644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (179459280).

138928644 is an abundant number, since it is smaller than the sum of its proper divisors (219989916).

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

138928644 is a wasteful number, since it uses less digits than its factorization.

138928644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561 (or 556 counting only the distinct ones).

The product of its digits is 331776, while the sum is 45.

The square root of 138928644 is about 11786.7995656158. The cubic root of 138928644 is about 517.9214909614.

The spelling of 138928644 in words is "one hundred thirty-eight million, nine hundred twenty-eight thousand, six hundred forty-four".