138993028 has 18 divisors (see below), whose sum is σ = 249039294. Its totient is φ = 67876704.

The previous prime is 138993017. The next prime is 138993059. The reversal of 138993028 is 820399831.

It is a happy number.

138993028 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 128867904 + 10125124 = 11352^2 + 3182^2 .

It is a Harshad number since it is a multiple of its sum of digits (43).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2001 + ... + 16792.

Almost surely, 2^138993028 is an apocalyptic number.

It is an amenable number.

138993028 is a deficient number, since it is larger than the sum of its proper divisors (110046266).

138993028 is a wasteful number, since it uses less digits than its factorization.

138993028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18883 (or 18838 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 43.

The square root of 138993028 is about 11789.5304401829. The cubic root of 138993028 is about 518.0014857617.

The spelling of 138993028 in words is "one hundred thirty-eight million, nine hundred ninety-three thousand, twenty-eight".