138991263 has 4 divisors (see below), whose sum is σ = 185321688. Its totient is φ = 92660840.

The previous prime is 138991253. The next prime is 138991291. The reversal of 138991263 is 362199831.

138991263 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 138991263 - 2⁴ = 138991247 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138991253) 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, 23165208 + ... + 23165213.

It is an arithmetic number, because the mean of its divisors is an integer number (46330422).

Almost surely, 2^138991263 is an apocalyptic number.

138991263 is a deficient number, since it is larger than the sum of its proper divisors (46330425).

138991263 is an equidigital number, since it uses as much as digits as its factorization.

138991263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46330424.

The product of its digits is 69984, while the sum is 42.

The square root of 138991263 is about 11789.4555853949. The cubic root of 138991263 is about 517.9992931422. Note that the first 3 decimals are identical.

The spelling of 138991263 in words is "one hundred thirty-eight million, nine hundred ninety-one thousand, two hundred sixty-three".