138978212 has 6 divisors (see below), whose sum is σ = 243211878. Its totient is φ = 69489104.

The previous prime is 138978211. The next prime is 138978223. The reversal of 138978212 is 212879831.

It can be written as a sum of positive squares in only one way, i.e., 90174016 + 48804196 = 9496^2 + 6986^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 138978212.

It is not an unprimeable number, because it can be changed into a prime (138978211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 17372273 + ... + 17372280.

It is an arithmetic number, because the mean of its divisors is an integer number (40535313).

Almost surely, 2^138978212 is an apocalyptic number.

It is an amenable number.

138978212 is a deficient number, since it is larger than the sum of its proper divisors (104233666).

138978212 is a wasteful number, since it uses less digits than its factorization.

138978212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34744557 (or 34744555 counting only the distinct ones).

The product of its digits is 48384, while the sum is 41.

The square root of 138978212 is about 11788.9020693193. The cubic root of 138978212 is about 517.9830796041.

The spelling of 138978212 in words is "one hundred thirty-eight million, nine hundred seventy-eight thousand, two hundred twelve".