217961 has 8 divisors (see below), whose sum is σ = 230400. Its totient is φ = 205920.

The previous prime is 217937. The next prime is 217969. The reversal of 217961 is 169712.

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 217961 - 2¹⁴ = 201577 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 217961.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 217961.

It is not an unprimeable number, because it can be changed into a prime (217969) 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, 2405 + ... + 2493.

It is an arithmetic number, because the mean of its divisors is an integer number (28800).

2²¹⁷⁹⁶¹ is an apocalyptic number.

It is an amenable number.

217961 is a deficient number, since it is larger than the sum of its proper divisors (12439).

217961 is an equidigital number, since it uses as much as digits as its factorization.

217961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199.

The product of its digits is 756, while the sum is 26.

The square root of 217961 is about 466.8629349177. The cubic root of 217961 is about 60.1810273431.

The spelling of 217961 in words is "two hundred seventeen thousand, nine hundred sixty-one".