217957 has 4 divisors (see below), whose sum is σ = 230796. Its totient is φ = 205120.

The previous prime is 217937. The next prime is 217969. The reversal of 217957 is 759712.

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 81796 + 136161 = 286^2 + 369^2 .

It is a cyclic number.

It is not a de Polignac number, because 217957 - 2⁷ = 217829 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 (217907) 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, 6394 + ... + 6427.

It is an arithmetic number, because the mean of its divisors is an integer number (57699).

2²¹⁷⁹⁵⁷ is an apocalyptic number.

It is an amenable number.

217957 is a deficient number, since it is larger than the sum of its proper divisors (12839).

217957 is a wasteful number, since it uses less digits than its factorization.

217957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12838.

The product of its digits is 4410, while the sum is 31.

The square root of 217957 is about 466.8586509855. The cubic root of 217957 is about 60.1806591953.

The spelling of 217957 in words is "two hundred seventeen thousand, nine hundred fifty-seven".