211220400221 has 2 divisors, whose sum is σ = 211220400222. Its totient is φ = 211220400220.

The previous prime is 211220400199. The next prime is 211220400227. The reversal of 211220400221 is 122004022112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 203265722500 + 7954677721 = 450850^2 + 89189^2 .

It is a cyclic number.

It is not a de Polignac number, because 211220400221 - 2¹⁰ = 211220399197 is a prime.

It is a super-2 number, since 2×211220400221² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 211220400221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211220400227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610200110 + 105610200111.

It is an arithmetic number, because the mean of its divisors is an integer number (105610200111).

Almost surely, 2^211220400221 is an apocalyptic number.

It is an amenable number.

211220400221 is a deficient number, since it is larger than the sum of its proper divisors (1).

211220400221 is an equidigital number, since it uses as much as digits as its factorization.

211220400221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 211220400221 its reverse (122004022112), we get a palindrome (333224422333).

The spelling of 211220400221 in words is "two hundred eleven billion, two hundred twenty million, four hundred thousand, two hundred twenty-one".