221211989 has 2 divisors, whose sum is σ = 221211990. Its totient is φ = 221211988.

The previous prime is 221211961. The next prime is 221212009. The reversal of 221211989 is 989112122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 214622500 + 6589489 = 14650^2 + 2567^2 .

It is a cyclic number.

It is not a de Polignac number, because 221211989 - 2⁸ = 221211733 is a prime.

It is a super-2 number, since 2×221211989² = 97869488154672242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221211589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110605994 + 110605995.

It is an arithmetic number, because the mean of its divisors is an integer number (110605995).

Almost surely, 2^221211989 is an apocalyptic number.

It is an amenable number.

221211989 is a deficient number, since it is larger than the sum of its proper divisors (1).

221211989 is an equidigital number, since it uses as much as digits as its factorization.

221211989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 35.

The square root of 221211989 is about 14873.1969999728. The cubic root of 221211989 is about 604.7876120824.

The spelling of 221211989 in words is "two hundred twenty-one million, two hundred eleven thousand, nine hundred eighty-nine".