221002021 has 2 divisors, whose sum is σ = 221002022. Its totient is φ = 221002020.

The previous prime is 221002003. The next prime is 221002031. The reversal of 221002021 is 120200122.

It is an a-pointer prime, because the next prime (221002031) can be obtained adding 221002021 to its sum of digits (10).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 210569121 + 10432900 = 14511^2 + 3230^2 .

It is a cyclic number.

It is not a de Polignac number, because 221002021 - 2⁹ = 221001509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221001989 and 221002007.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221002031) 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, 110501010 + 110501011.

It is an arithmetic number, because the mean of its divisors is an integer number (110501011).

Almost surely, 2^221002021 is an apocalyptic number.

It is an amenable number.

221002021 is a deficient number, since it is larger than the sum of its proper divisors (1).

221002021 is an equidigital number, since it uses as much as digits as its factorization.

221002021 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 10.

The square root of 221002021 is about 14866.1367207489. The cubic root of 221002021 is about 604.5962025597.

Adding to 221002021 its reverse (120200122), we get a palindrome (341202143).

The spelling of 221002021 in words is "two hundred twenty-one million, two thousand, twenty-one".