221005121 has 2 divisors, whose sum is σ = 221005122. Its totient is φ = 221005120.

The previous prime is 221005097. The next prime is 221005153. The reversal of 221005121 is 121500122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 205520896 + 15484225 = 14336^2 + 3935^2 .

It is a cyclic number.

It is not a de Polignac number, because 221005121 - 2¹⁴ = 220988737 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 221005096 and 221005105.

It is not a weakly prime, because it can be changed into another prime (221002121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110502560 + 110502561.

It is an arithmetic number, because the mean of its divisors is an integer number (110502561).

Almost surely, 2^221005121 is an apocalyptic number.

It is an amenable number.

221005121 is a deficient number, since it is larger than the sum of its proper divisors (1).

221005121 is an equidigital number, since it uses as much as digits as its factorization.

221005121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 221005121 is about 14866.2409841896. The cubic root of 221005121 is about 604.5990294411.

Adding to 221005121 its reverse (121500122), we get a palindrome (342505243).

The spelling of 221005121 in words is "two hundred twenty-one million, five thousand, one hundred twenty-one".