221002121 has 2 divisors, whose sum is σ = 221002122. Its totient is φ = 221002120.

The previous prime is 221002097. The next prime is 221002151. The reversal of 221002121 is 121200122.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 114169225 + 106832896 = 10685^2 + 10336^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221002121 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221002151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110501060 + 110501061.

It is an arithmetic number, because the mean of its divisors is an integer number (110501061).

Almost surely, 2^221002121 is an apocalyptic number.

It is an amenable number.

221002121 is a deficient number, since it is larger than the sum of its proper divisors (1).

221002121 is an equidigital number, since it uses as much as digits as its factorization.

221002121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 221002121 is about 14866.1400840971. The cubic root of 221002121 is about 604.5962937499.

Adding to 221002121 its reverse (121200122), we get a palindrome (342202243).

The spelling of 221002121 in words is "two hundred twenty-one million, two thousand, one hundred twenty-one".