221989 has 2 divisors, whose sum is σ = 221990. Its totient is φ = 221988.

The previous prime is 221987. The next prime is 221999. The reversal of 221989 is 989122.

221989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 220900 + 1089 = 470^2 + 33^2 .

It is a cyclic number.

It is not a de Polignac number, because 221989 - 2¹ = 221987 is a prime.

It is a super-2 number, since 2×221989² = 98558232242, which contains 22 as substring.

Together with 221987, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 221989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110994 + 110995.

It is an arithmetic number, because the mean of its divisors is an integer number (110995).

2²²¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

221989 is a deficient number, since it is larger than the sum of its proper divisors (1).

221989 is an equidigital number, since it uses as much as digits as its factorization.

221989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 31.

The square root of 221989 is about 471.1570863311. The cubic root of 221989 is about 60.5494893654.

The spelling of 221989 in words is "two hundred twenty-one thousand, nine hundred eighty-nine".