221709 has 8 divisors (see below), whose sum is σ = 297792. Its totient is φ = 146720.

The previous prime is 221707. The next prime is 221713. The reversal of 221709 is 907122.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 221709 - 2¹ = 221707 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221707) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 649 + ... + 929.

It is an arithmetic number, because the mean of its divisors is an integer number (37224).

2²²¹⁷⁰⁹ is an apocalyptic number.

It is an amenable number.

221709 is a deficient number, since it is larger than the sum of its proper divisors (76083).

221709 is a wasteful number, since it uses less digits than its factorization.

221709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 547.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 221709 is about 470.8598517606. The cubic root of 221709 is about 60.5240211514.

The spelling of 221709 in words is "two hundred twenty-one thousand, seven hundred nine".