309221 has 4 divisors (see below), whose sum is σ = 337344. Its totient is φ = 281100.

The previous prime is 309193. The next prime is 309223. The reversal of 309221 is 122903.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122903 = 11 ⋅11173.

It is a cyclic number.

It is not a de Polignac number, because 309221 - 2⁶ = 309157 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 309221.

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 309221.

It is not an unprimeable number, because it can be changed into a prime (309223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14045 + ... + 14066.

It is an arithmetic number, because the mean of its divisors is an integer number (84336).

2³⁰⁹²²¹ is an apocalyptic number.

It is an amenable number.

309221 is a deficient number, since it is larger than the sum of its proper divisors (28123).

309221 is a wasteful number, since it uses less digits than its factorization.

309221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28122.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 309221 is about 556.0764335952. The cubic root of 309221 is about 67.6222567144.

It can be divided in two parts, 3092 and 21, that added together give a palindrome (3113).

The spelling of 309221 in words is "three hundred nine thousand, two hundred twenty-one".