221211212021 has 2 divisors, whose sum is σ = 221211212022. Its totient is φ = 221211212020.

The previous prime is 221211212017. The next prime is 221211212077. The reversal of 221211212021 is 120212112122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 115855140625 + 105356071396 = 340375^2 + 324586^2 .

It is a cyclic number.

It is not a de Polignac number, because 221211212021 - 2² = 221211212017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221211211021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110605606010 + 110605606011.

It is an arithmetic number, because the mean of its divisors is an integer number (110605606011).

Almost surely, 2^221211212021 is an apocalyptic number.

It is an amenable number.

221211212021 is a deficient number, since it is larger than the sum of its proper divisors (1).

221211212021 is an equidigital number, since it uses as much as digits as its factorization.

221211212021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 221211212021 its reverse (120212112122), we get a palindrome (341423324143).

The spelling of 221211212021 in words is "two hundred twenty-one billion, two hundred eleven million, two hundred twelve thousand, twenty-one".