138891946 has 4 divisors (see below), whose sum is σ = 208337922. Its totient is φ = 69445972.

The previous prime is 138891923. The next prime is 138891947. The reversal of 138891946 is 649198831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 649198831 = 3739 ⋅173629.

It can be written as a sum of positive squares in only one way, i.e., 117961321 + 20930625 = 10861^2 + 4575^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 138891946.

It is not an unprimeable number, because it can be changed into a prime (138891947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34722985 + ... + 34722988.

Almost surely, 2^138891946 is an apocalyptic number.

138891946 is a deficient number, since it is larger than the sum of its proper divisors (69445976).

138891946 is an equidigital number, since it uses as much as digits as its factorization.

138891946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69445975.

The product of its digits is 373248, while the sum is 49.

The square root of 138891946 is about 11785.2427213019. The cubic root of 138891946 is about 517.8758839598.

The spelling of 138891946 in words is "one hundred thirty-eight million, eight hundred ninety-one thousand, nine hundred forty-six".