221212009 has 2 divisors, whose sum is σ = 221212010. Its totient is φ = 221212008.

The previous prime is 221211989. The next prime is 221212021. The reversal of 221212009 is 900212122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 121771225 + 99440784 = 11035^2 + 9972^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221212009 is a prime.

It is not a weakly prime, because it can be changed into another prime (221212049) 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, 110606004 + 110606005.

It is an arithmetic number, because the mean of its divisors is an integer number (110606005).

Almost surely, 2^221212009 is an apocalyptic number.

It is an amenable number.

221212009 is a deficient number, since it is larger than the sum of its proper divisors (1).

221212009 is an equidigital number, since it uses as much as digits as its factorization.

221212009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 221212009 is about 14873.1976723232. The cubic root of 221212009 is about 604.7876303089.

The spelling of 221212009 in words is "two hundred twenty-one million, two hundred twelve thousand, nine".