21110201221 has 2 divisors, whose sum is σ = 21110201222. Its totient is φ = 21110201220.

The previous prime is 21110201213. The next prime is 21110201227. The reversal of 21110201221 is 12210201112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21078684225 + 31516996 = 145185^2 + 5614^2 .

It is a cyclic number.

It is not a de Polignac number, because 21110201221 - 2³ = 21110201213 is a prime.

It is a super-2 number, since 2×21110201221² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21110201227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555100610 + 10555100611.

It is an arithmetic number, because the mean of its divisors is an integer number (10555100611).

Almost surely, 2^21110201221 is an apocalyptic number.

It is an amenable number.

21110201221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21110201221 is an equidigital number, since it uses as much as digits as its factorization.

21110201221 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 21110201221 its reverse (12210201112), we get a palindrome (33320402333).

The spelling of 21110201221 in words is "twenty-one billion, one hundred ten million, two hundred one thousand, two hundred twenty-one".