211220221021 has 2 divisors, whose sum is σ = 211220221022. Its totient is φ = 211220221020.

The previous prime is 211220221019. The next prime is 211220221097. The reversal of 211220221021 is 120122022112.

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., 200154232996 + 11065988025 = 447386^2 + 105195^2 .

It is a cyclic number.

It is not a de Polignac number, because 211220221021 - 2¹ = 211220221019 is a prime.

It is a super-2 number, since 2×211220221021² (a number of 23 digits) contains 22 as substring.

Together with 211220221019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 211220220986 and 211220221004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211220221001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610110510 + 105610110511.

It is an arithmetic number, because the mean of its divisors is an integer number (105610110511).

Almost surely, 2^211220221021 is an apocalyptic number.

It is an amenable number.

211220221021 is a deficient number, since it is larger than the sum of its proper divisors (1).

211220221021 is an equidigital number, since it uses as much as digits as its factorization.

211220221021 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 16.

Adding to 211220221021 its reverse (120122022112), we get a palindrome (331342243133).

The spelling of 211220221021 in words is "two hundred eleven billion, two hundred twenty million, two hundred twenty-one thousand, twenty-one".