221979 has 8 divisors (see below), whose sum is σ = 301072. Its totient is φ = 145440.

The previous prime is 221957. The next prime is 221987. The reversal of 221979 is 979122.

221979 is nontrivially palindromic in base 2.

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

It is not a de Polignac number, because 221979 - 2⁸ = 221723 is a prime.

It is a Duffinian number.

221979 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (221909) 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, 424 + ... + 789.

It is an arithmetic number, because the mean of its divisors is an integer number (37634).

2²²¹⁹⁷⁹ is an apocalyptic number.

221979 is a deficient number, since it is larger than the sum of its proper divisors (79093).

221979 is a wasteful number, since it uses less digits than its factorization.

221979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1277.

The product of its digits is 2268, while the sum is 30.

The square root of 221979 is about 471.1464740397. The cubic root of 221979 is about 60.5485801552.

The spelling of 221979 in words is "two hundred twenty-one thousand, nine hundred seventy-nine".