211221212021 has 2 divisors, whose sum is σ = 211221212022. Its totient is φ = 211221212020.

The previous prime is 211221212003. The next prime is 211221212051. The reversal of 211221212021 is 120212122112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 123050817796 + 88170394225 = 350786^2 + 296935^2 .

It is a cyclic number.

It is not a de Polignac number, because 211221212021 - 2¹⁴ = 211221195637 is a prime.

It is a super-2 number, since 2×211221212021² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211221212051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610606010 + 105610606011.

It is an arithmetic number, because the mean of its divisors is an integer number (105610606011).

Almost surely, 2^211221212021 is an apocalyptic number.

It is an amenable number.

211221212021 is a deficient number, since it is larger than the sum of its proper divisors (1).

211221212021 is an equidigital number, since it uses as much as digits as its factorization.

211221212021 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 211221212021 its reverse (120212122112), we get a palindrome (331433334133).

The spelling of 211221212021 in words is "two hundred eleven billion, two hundred twenty-one million, two hundred twelve thousand, twenty-one".