217990 has 8 divisors (see below), whose sum is σ = 392400. Its totient is φ = 87192.

The previous prime is 217981. The next prime is 218003. The reversal of 217990 is 99712.

217990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10890 + ... + 10909.

It is an arithmetic number, because the mean of its divisors is an integer number (49050).

2²¹⁷⁹⁹⁰ is an apocalyptic number.

217990 is a deficient number, since it is larger than the sum of its proper divisors (174410).

217990 is a wasteful number, since it uses less digits than its factorization.

217990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21806.

The product of its (nonzero) digits is 1134, while the sum is 28.

The square root of 217990 is about 466.8939922509. The cubic root of 217990 is about 60.1836962799.

The spelling of 217990 in words is "two hundred seventeen thousand, nine hundred ninety".