217312 has 12 divisors (see below), whose sum is σ = 427896. Its totient is φ = 108640.

The previous prime is 217309. The next prime is 217313. The reversal of 217312 is 213712.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3364 + ... + 3427.

It is an arithmetic number, because the mean of its divisors is an integer number (35658).

2²¹⁷³¹² is an apocalyptic number.

It is an amenable number.

217312 is a deficient number, since it is larger than the sum of its proper divisors (210584).

217312 is an equidigital number, since it uses as much as digits as its factorization.

217312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6801 (or 6793 counting only the distinct ones).

The product of its digits is 84, while the sum is 16.

The square root of 217312 is about 466.1673519242. The cubic root of 217312 is about 60.1212363456.

Subtracting from 217312 its reverse (213712), we obtain a square (3600 = 60²).

It can be divided in two parts, 217 and 312, that added together give a square (529 = 23²).

The spelling of 217312 in words is "two hundred seventeen thousand, three hundred twelve", and thus it is an iban number.