138633391 has 4 divisors (see below), whose sum is σ = 149297512. Its totient is φ = 127969272.

The previous prime is 138633389. The next prime is 138633403. The reversal of 138633391 is 193336831.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 138633391 - 2¹ = 138633389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 138633391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138633301) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5332041 + ... + 5332066.

It is an arithmetic number, because the mean of its divisors is an integer number (37324378).

Almost surely, 2^138633391 is an apocalyptic number.

138633391 is a deficient number, since it is larger than the sum of its proper divisors (10664121).

138633391 is a wasteful number, since it uses less digits than its factorization.

138633391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10664120.

The product of its digits is 34992, while the sum is 37.

The square root of 138633391 is about 11774.2681725872. The cubic root of 138633391 is about 517.5543328641.

The spelling of 138633391 in words is "one hundred thirty-eight million, six hundred thirty-three thousand, three hundred ninety-one".