139869209 has 4 divisors (see below), whose sum is σ = 139978020. Its totient is φ = 139760400.

The previous prime is 139869199. The next prime is 139869271. The reversal of 139869209 is 902968931.

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 13801225 + 126067984 = 3715^2 + 11228^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-139869209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (139862209) 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, 52454 + ... + 55055.

It is an arithmetic number, because the mean of its divisors is an integer number (34994505).

Almost surely, 2^139869209 is an apocalyptic number.

It is an amenable number.

139869209 is a deficient number, since it is larger than the sum of its proper divisors (108811).

139869209 is a wasteful number, since it uses less digits than its factorization.

139869209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108810.

The product of its (nonzero) digits is 209952, while the sum is 47.

The square root of 139869209 is about 11826.6313462456. The cubic root of 139869209 is about 519.0876618298.

It can be divided in two parts, 1398 and 69209, that added together give a palindrome (70607).

The spelling of 139869209 in words is "one hundred thirty-nine million, eight hundred sixty-nine thousand, two hundred nine".