21001222110221 has 2 divisors, whose sum is σ = 21001222110222. Its totient is φ = 21001222110220.

The previous prime is 21001222110191. The next prime is 21001222110233. The reversal of 21001222110221 is 12201122210012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13300536060100 + 7700686050121 = 3646990^2 + 2775011^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001222110221 - 2²² = 21001217915917 is a prime.

It is a super-3 number, since 3×21001222110221³ (a number of 41 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21001222110221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001222130221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500611055110 + 10500611055111.

It is an arithmetic number, because the mean of its divisors is an integer number (10500611055111).

Almost surely, 2^{21001222110221} is an apocalyptic number.

It is an amenable number.

21001222110221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001222110221 is an equidigital number, since it uses as much as digits as its factorization.

21001222110221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21001222110221 its reverse (12201122210012), we get a palindrome (33202344320233).

It can be divided in two parts, 21001 and 222110221, that added together give a palindrome (222131222).

The spelling of 21001222110221 in words is "twenty-one trillion, one billion, two hundred twenty-two million, one hundred ten thousand, two hundred twenty-one".