221222100821 has 2 divisors, whose sum is σ = 221222100822. Its totient is φ = 221222100820.

The previous prime is 221222100763. The next prime is 221222100829. The reversal of 221222100821 is 128001222122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185277732721 + 35944368100 = 430439^2 + 189590^2 .

It is a cyclic number.

It is not a de Polignac number, because 221222100821 - 2¹⁰ = 221222099797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221222100829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110611050410 + 110611050411.

It is an arithmetic number, because the mean of its divisors is an integer number (110611050411).

Almost surely, 2^221222100821 is an apocalyptic number.

It is an amenable number.

221222100821 is a deficient number, since it is larger than the sum of its proper divisors (1).

221222100821 is an equidigital number, since it uses as much as digits as its factorization.

221222100821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 512, while the sum is 23.

Adding to 221222100821 its reverse (128001222122), we get a palindrome (349223322943).

The spelling of 221222100821 in words is "two hundred twenty-one billion, two hundred twenty-two million, one hundred thousand, eight hundred twenty-one".