217812 has 24 divisors (see below), whose sum is σ = 581056. Its totient is φ = 62208.

The previous prime is 217793. The next prime is 217823. The reversal of 217812 is 218712.

217812 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an Ulam number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 217812.

It is an unprimeable number.

217812 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1213 + ... + 1380.

2²¹⁷⁸¹² is an apocalyptic number.

It is an amenable number.

217812 is an abundant number, since it is smaller than the sum of its proper divisors (363244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217812 is a wasteful number, since it uses less digits than its factorization.

217812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2607 (or 2605 counting only the distinct ones).

The product of its digits is 224, while the sum is 21.

The square root of 217812 is about 466.7033318930. The cubic root of 217812 is about 60.1673107957.

Subtracting 217812 from its reverse (218712), we obtain a square (900 = 30²).

The spelling of 217812 in words is "two hundred seventeen thousand, eight hundred twelve".