221427989 has 2 divisors, whose sum is σ = 221427990. Its totient is φ = 221427988.

The previous prime is 221427971. The next prime is 221427991. The reversal of 221427989 is 989724122.

221427989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 215943025 + 5484964 = 14695^2 + 2342^2 .

It is a cyclic number.

It is not a de Polignac number, because 221427989 - 2²⁰ = 220379413 is a prime.

Together with 221427991, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221427949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110713994 + 110713995.

It is an arithmetic number, because the mean of its divisors is an integer number (110713995).

Almost surely, 2^221427989 is an apocalyptic number.

It is an amenable number.

221427989 is a deficient number, since it is larger than the sum of its proper divisors (1).

221427989 is an equidigital number, since it uses as much as digits as its factorization.

221427989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 44.

The square root of 221427989 is about 14880.4566126178. The cubic root of 221427989 is about 604.9843941060.

It can be divided in two parts, 2214 and 27989, that added together give a palindrome (30203).

The spelling of 221427989 in words is "two hundred twenty-one million, four hundred twenty-seven thousand, nine hundred eighty-nine".