221428989 has 6 divisors (see below), whose sum is σ = 319841886. Its totient is φ = 147619320.

The previous prime is 221428913. The next prime is 221428997. The reversal of 221428989 is 989824122.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 181360089 + 40068900 = 13467^2 + 6330^2 .

It is not a de Polignac number, because 221428989 - 2⁸ = 221428733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221428189) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12301602 + ... + 12301619.

It is an arithmetic number, because the mean of its divisors is an integer number (53306981).

Almost surely, 2^221428989 is an apocalyptic number.

It is an amenable number.

221428989 is a deficient number, since it is larger than the sum of its proper divisors (98412897).

221428989 is a wasteful number, since it uses less digits than its factorization.

221428989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24603227 (or 24603224 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 221428989 is about 14880.4902136993. The cubic root of 221428989 is about 604.9853048362.

The spelling of 221428989 in words is "two hundred twenty-one million, four hundred twenty-eight thousand, nine hundred eighty-nine".