217965 has 16 divisors (see below), whose sum is σ = 380736. Its totient is φ = 105600.

The previous prime is 217937. The next prime is 217969. The reversal of 217965 is 569712.

It is not a de Polignac number, because 217965 - 2⁵ = 217933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217969) 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, 496 + ... + 825.

It is an arithmetic number, because the mean of its divisors is an integer number (23796).

2²¹⁷⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

217965 is a deficient number, since it is larger than the sum of its proper divisors (162771).

217965 is a wasteful number, since it uses less digits than its factorization.

217965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1340.

The product of its digits is 3780, while the sum is 30.

The square root of 217965 is about 466.8672188107. The cubic root of 217965 is about 60.1813954864.

Subtracting from 217965 its product of digits (3780), we obtain a triangular number (214185 = T₆₅₄).

The spelling of 217965 in words is "two hundred seventeen thousand, nine hundred sixty-five".