138649988 has 6 divisors (see below), whose sum is σ = 242637486. Its totient is φ = 69324992.

The previous prime is 138649981. The next prime is 138649993. The reversal of 138649988 is 889946831.

It can be written as a sum of positive squares in only one way, i.e., 138250564 + 399424 = 11758^2 + 632^2 .

It is not an unprimeable number, because it can be changed into a prime (138649981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 17331245 + ... + 17331252.

It is an arithmetic number, because the mean of its divisors is an integer number (40439581).

Almost surely, 2^138649988 is an apocalyptic number.

It is an amenable number.

138649988 is a deficient number, since it is larger than the sum of its proper divisors (103987498).

138649988 is a wasteful number, since it uses less digits than its factorization.

138649988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34662501 (or 34662499 counting only the distinct ones).

The product of its digits is 2985984, while the sum is 56.

The square root of 138649988 is about 11774.9729511367. The cubic root of 138649988 is about 517.5749856723.

The spelling of 138649988 in words is "one hundred thirty-eight million, six hundred forty-nine thousand, nine hundred eighty-eight".