209817157 has 16 divisors (see below), whose sum is σ = 234912960. Its totient is φ = 185785600.

The previous prime is 209817149. The next prime is 209817163. The reversal of 209817157 is 751718902.

It is not a de Polignac number, because 209817157 - 2³ = 209817149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209817107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71907 + ... + 74767.

It is an arithmetic number, because the mean of its divisors is an integer number (14682060).

Almost surely, 2^209817157 is an apocalyptic number.

It is an amenable number.

209817157 is a deficient number, since it is larger than the sum of its proper divisors (25095803).

209817157 is a wasteful number, since it uses less digits than its factorization.

209817157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3044.

The product of its (nonzero) digits is 35280, while the sum is 40.

The square root of 209817157 is about 14485.0666895255. The cubic root of 209817157 is about 594.2196365312.

The spelling of 209817157 in words is "two hundred nine million, eight hundred seventeen thousand, one hundred fifty-seven".