217997 has 8 divisors (see below), whose sum is σ = 241080. Its totient is φ = 195840.

The previous prime is 217981. The next prime is 218003. The reversal of 217997 is 799712.

It can be written as a sum of positive squares in 4 ways, for example, as 5476 + 212521 = 74^2 + 461^2 .

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 217997 - 2⁴ = 217981 is a prime.

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 7 ways as a sum of consecutive naturals, for example, 329 + ... + 737.

It is an arithmetic number, because the mean of its divisors is an integer number (30135).

2²¹⁷⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

217997 is a deficient number, since it is larger than the sum of its proper divisors (23083).

217997 is a wasteful number, since it uses less digits than its factorization.

217997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 463.

The product of its digits is 7938, while the sum is 35.

The square root of 217997 is about 466.9014885391. The cubic root of 217997 is about 60.1843404706.

The spelling of 217997 in words is "two hundred seventeen thousand, nine hundred ninety-seven".