138919691 has 4 divisors (see below), whose sum is σ = 138949800. Its totient is φ = 138889584.

The previous prime is 138919681. The next prime is 138919709. The reversal of 138919691 is 196919831.

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 138919691 - 2¹⁰ = 138918667 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138919661) 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, 6521 + ... + 17898.

It is an arithmetic number, because the mean of its divisors is an integer number (34737450).

Almost surely, 2^138919691 is an apocalyptic number.

138919691 is a deficient number, since it is larger than the sum of its proper divisors (30109).

138919691 is an equidigital number, since it uses as much as digits as its factorization.

138919691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30108.

The product of its digits is 104976, while the sum is 47.

The square root of 138919691 is about 11786.4197702271. The cubic root of 138919691 is about 517.9103652242.

The spelling of 138919691 in words is "one hundred thirty-eight million, nine hundred nineteen thousand, six hundred ninety-one".