138621893 has 4 divisors (see below), whose sum is σ = 146776140. Its totient is φ = 130467648.

The previous prime is 138621877. The next prime is 138621907. The reversal of 138621893 is 398126831.

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

It can be written as a sum of positive squares in 2 ways, for example, as 117983044 + 20638849 = 10862^2 + 4543^2 .

It is a cyclic number.

It is not a de Polignac number, because 138621893 - 2⁴ = 138621877 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 138621893.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138621823) 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, 4077098 + ... + 4077131.

It is an arithmetic number, because the mean of its divisors is an integer number (36694035).

Almost surely, 2^138621893 is an apocalyptic number.

It is an amenable number.

138621893 is a deficient number, since it is larger than the sum of its proper divisors (8154247).

138621893 is an equidigital number, since it uses as much as digits as its factorization.

138621893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8154246.

The product of its digits is 62208, while the sum is 41.

The square root of 138621893 is about 11773.7798943245. The cubic root of 138621893 is about 517.5400241318.

The spelling of 138621893 in words is "one hundred thirty-eight million, six hundred twenty-one thousand, eight hundred ninety-three".