139706209 has 8 divisors (see below), whose sum is σ = 146284992. Its totient is φ = 133169520.

The previous prime is 139706197. The next prime is 139706219. The reversal of 139706209 is 902607931.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 139706209 - 2²¹ = 137609057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (139706219) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3627 + ... + 17104.

It is an arithmetic number, because the mean of its divisors is an integer number (18285624).

Almost surely, 2^139706209 is an apocalyptic number.

It is an amenable number.

139706209 is a deficient number, since it is larger than the sum of its proper divisors (6578783).

139706209 is a wasteful number, since it uses less digits than its factorization.

139706209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21047.

The product of its (nonzero) digits is 20412, while the sum is 37.

The square root of 139706209 is about 11819.7381104659. The cubic root of 139706209 is about 518.8859396192.

The spelling of 139706209 in words is "one hundred thirty-nine million, seven hundred six thousand, two hundred nine".