209872117 has 16 divisors (see below), whose sum is σ = 259907200. Its totient is φ = 165022272.

The previous prime is 209872099. The next prime is 209872151. The reversal of 209872117 is 711278902.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209872117 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209872417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7759 + ... + 21907.

It is an arithmetic number, because the mean of its divisors is an integer number (16244200).

Almost surely, 2^209872117 is an apocalyptic number.

It is an amenable number.

209872117 is a deficient number, since it is larger than the sum of its proper divisors (50035083).

209872117 is a wasteful number, since it uses less digits than its factorization.

209872117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14332.

The product of its (nonzero) digits is 14112, while the sum is 37.

The square root of 209872117 is about 14486.9636915401. The cubic root of 209872117 is about 594.2715157651.

It can be divided in two parts, 20987 and 2117, that added together give a square (23104 = 152²).

The spelling of 209872117 in words is "two hundred nine million, eight hundred seventy-two thousand, one hundred seventeen".