209117639 has 2 divisors, whose sum is σ = 209117640. Its totient is φ = 209117638.

The previous prime is 209117611. The next prime is 209117651. The reversal of 209117639 is 936711902.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 209117639 - 2¹² = 209113543 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209117039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104558819 + 104558820.

It is an arithmetic number, because the mean of its divisors is an integer number (104558820).

Almost surely, 2^209117639 is an apocalyptic number.

209117639 is a deficient number, since it is larger than the sum of its proper divisors (1).

209117639 is an equidigital number, since it uses as much as digits as its factorization.

209117639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20412, while the sum is 38.

The square root of 209117639 is about 14460.9003523294. The cubic root of 209117639 is about 593.5585369149.

The spelling of 209117639 in words is "two hundred nine million, one hundred seventeen thousand, six hundred thirty-nine".