139931009 has 4 divisors (see below), whose sum is σ = 140007360. Its totient is φ = 139854660.

The previous prime is 139930979. The next prime is 139931021. The reversal of 139931009 is 900139931.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 900139931 = 59 ⋅15256609.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-139931009 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 139931009.

It is not an unprimeable number, because it can be changed into a prime (139931059) 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, 35357 + ... + 39114.

It is an arithmetic number, because the mean of its divisors is an integer number (35001840).

Almost surely, 2^139931009 is an apocalyptic number.

It is an amenable number.

139931009 is a deficient number, since it is larger than the sum of its proper divisors (76351).

139931009 is an equidigital number, since it uses as much as digits as its factorization.

139931009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76350.

The product of its (nonzero) digits is 6561, while the sum is 35.

The square root of 139931009 is about 11829.2438050790. The cubic root of 139931009 is about 519.1641020370.

The spelling of 139931009 in words is "one hundred thirty-nine million, nine hundred thirty-one thousand, nine".