221685 has 8 divisors (see below), whose sum is σ = 354720. Its totient is φ = 118224.

The previous prime is 221677. The next prime is 221707. The reversal of 221685 is 586122.

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

It is not a de Polignac number, because 221685 - 2³ = 221677 is a prime.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 7375 + ... + 7404.

It is an arithmetic number, because the mean of its divisors is an integer number (44340).

2²²¹⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

221685 is a deficient number, since it is larger than the sum of its proper divisors (133035).

221685 is a wasteful number, since it uses less digits than its factorization.

221685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14787.

The product of its digits is 960, while the sum is 24.

The square root of 221685 is about 470.8343657806. The cubic root of 221685 is about 60.5218371641.

The spelling of 221685 in words is "two hundred twenty-one thousand, six hundred eighty-five".