20101221201221 has 2 divisors, whose sum is σ = 20101221201222. Its totient is φ = 20101221201220.

The previous prime is 20101221201167. The next prime is 20101221201233. The reversal of 20101221201221 is 12210212210102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14912456572225 + 5188764628996 = 3861665^2 + 2277886^2 .

It is a cyclic number.

It is not a de Polignac number, because 20101221201221 - 2⁶ = 20101221201157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20101221201221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20101221201821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10050610600610 + 10050610600611.

It is an arithmetic number, because the mean of its divisors is an integer number (10050610600611).

Almost surely, 2^{20101221201221} is an apocalyptic number.

It is an amenable number.

20101221201221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20101221201221 is an equidigital number, since it uses as much as digits as its factorization.

20101221201221 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 17.

Adding to 20101221201221 its reverse (12210212210102), we get a palindrome (32311433411323).

The spelling of 20101221201221 in words is "twenty trillion, one hundred one billion, two hundred twenty-one million, two hundred one thousand, two hundred twenty-one".