138645906 has 16 divisors (see below), whose sum is σ = 316905024. Its totient is φ = 39613104.

The previous prime is 138645901. The next prime is 138645917. The reversal of 138645906 is 609546831.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 3301093 = 138645906 / (1 + 3 + 8 + 6 + 4 + 5 + 9 + 0 + 6).

It is not an unprimeable number, because it can be changed into a prime (138645901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1650505 + ... + 1650588.

It is an arithmetic number, because the mean of its divisors is an integer number (19806564).

Almost surely, 2^138645906 is an apocalyptic number.

138645906 is an abundant number, since it is smaller than the sum of its proper divisors (178259118).

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

138645906 is a wasteful number, since it uses less digits than its factorization.

138645906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3301105.

The product of its (nonzero) digits is 155520, while the sum is 42.

The square root of 138645906 is about 11774.7996161294. The cubic root of 138645906 is about 517.5699063070.

The spelling of 138645906 in words is "one hundred thirty-eight million, six hundred forty-five thousand, nine hundred six".