21001111221121 has 2 divisors, whose sum is σ = 21001111221122. Its totient is φ = 21001111221120.

The previous prime is 21001111221067. The next prime is 21001111221133. The reversal of 21001111221121 is 12112211110012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20994174163600 + 6937057521 = 4581940^2 + 83289^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001111221121 - 2⁷ = 21001111220993 is a prime.

It is a super-3 number, since 3×21001111221121³ (a number of 41 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21001111221095 and 21001111221104.

It is not a weakly prime, because it can be changed into another prime (21001121221121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500555610560 + 10500555610561.

It is an arithmetic number, because the mean of its divisors is an integer number (10500555610561).

Almost surely, 2^{21001111221121} is an apocalyptic number.

It is an amenable number.

21001111221121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001111221121 is an equidigital number, since it uses as much as digits as its factorization.

21001111221121 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 16.

Adding to 21001111221121 its reverse (12112211110012), we get a palindrome (33113322331133).

The spelling of 21001111221121 in words is "twenty-one trillion, one billion, one hundred eleven million, two hundred twenty-one thousand, one hundred twenty-one".