21201221101001 has 2 divisors, whose sum is σ = 21201221101002. Its totient is φ = 21201221101000.

The previous prime is 21201221100991. The next prime is 21201221101019. The reversal of 21201221101001 is 10010112210212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13385975929225 + 7815245171776 = 3658685^2 + 2795576^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201221101001 - 2³⁴ = 21184041231817 is a prime.

It is not a weakly prime, because it can be changed into another prime (21201221101061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600610550500 + 10600610550501.

It is an arithmetic number, because the mean of its divisors is an integer number (10600610550501).

Almost surely, 2^{21201221101001} is an apocalyptic number.

It is an amenable number.

21201221101001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201221101001 is an equidigital number, since it uses as much as digits as its factorization.

21201221101001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21201221101001 its reverse (10010112210212), we get a palindrome (31211333311213).

The spelling of 21201221101001 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-one million, one hundred one thousand, one".