211221000100021 has 2 divisors, whose sum is σ = 211221000100022. Its totient is φ = 211221000100020.

The previous prime is 211221000100009. The next prime is 211221000100031. The reversal of 211221000100021 is 120001000122112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 206397327906225 + 4823672193796 = 14366535^2 + 2196286^2 .

It is a cyclic number.

It is not a de Polignac number, because 211221000100021 - 2²¹ = 211220998002869 is a prime.

It is a super-2 number, since 2×211221000100021² (a number of 29 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 211221000099974 and 211221000100010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211221000100031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610500050010 + 105610500050011.

It is an arithmetic number, because the mean of its divisors is an integer number (105610500050011).

Almost surely, 2^{211221000100021} is an apocalyptic number.

It is an amenable number.

211221000100021 is a deficient number, since it is larger than the sum of its proper divisors (1).

211221000100021 is an equidigital number, since it uses as much as digits as its factorization.

211221000100021 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 13.

Adding to 211221000100021 its reverse (120001000122112), we get a palindrome (331222000222133).

The spelling of 211221000100021 in words is "two hundred eleven trillion, two hundred twenty-one billion, one hundred thousand, twenty-one".