139565981 has 4 divisors (see below), whose sum is σ = 139593600. Its totient is φ = 139538364.

The previous prime is 139565953. The next prime is 139566041. The reversal of 139565981 is 189565931.

139565981 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 139565981 - 2²⁶ = 72457117 is a prime.

It is a super-2 number, since 2×139565981² = 38957326104984722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (139565281) 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, 3821 + ... + 17138.

It is an arithmetic number, because the mean of its divisors is an integer number (34898400).

Almost surely, 2^139565981 is an apocalyptic number.

It is an amenable number.

139565981 is a deficient number, since it is larger than the sum of its proper divisors (27619).

139565981 is an equidigital number, since it uses as much as digits as its factorization.

139565981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27618.

The product of its digits is 291600, while the sum is 47.

The square root of 139565981 is about 11813.8046792725. The cubic root of 139565981 is about 518.7122735229.

It can be divided in two parts, 1395 and 65981, that added together give a palindrome (67376).

The spelling of 139565981 in words is "one hundred thirty-nine million, five hundred sixty-five thousand, nine hundred eighty-one".