138719991 has 8 divisors (see below), whose sum is σ = 186867184. Its totient is φ = 91526400.

The previous prime is 138719989. The next prime is 138720037. The reversal of 138719991 is 199917831.

It is a happy number.

138719991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138719991 - 2¹ = 138719989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 138719991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138719981) 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, 238060 + ... + 238641.

It is an arithmetic number, because the mean of its divisors is an integer number (23358398).

Almost surely, 2^138719991 is an apocalyptic number.

138719991 is a deficient number, since it is larger than the sum of its proper divisors (48147193).

138719991 is an equidigital number, since it uses as much as digits as its factorization.

138719991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 476801.

The product of its digits is 122472, while the sum is 48.

The square root of 138719991 is about 11777.9451093983. The cubic root of 138719991 is about 517.6620771710.

The spelling of 138719991 in words is "one hundred thirty-eight million, seven hundred nineteen thousand, nine hundred ninety-one".