21001122111209 has 2 divisors, whose sum is σ = 21001122111210. Its totient is φ = 21001122111208.

The previous prime is 21001122111139. The next prime is 21001122111223. The reversal of 21001122111209 is 90211122110012.

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., 19314240671209 + 1686881440000 = 4394797^2 + 1298800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001122111209 - 2⁴⁴ = 3408936066793 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001122111709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500561055604 + 10500561055605.

It is an arithmetic number, because the mean of its divisors is an integer number (10500561055605).

Almost surely, 2^{21001122111209} is an apocalyptic number.

It is an amenable number.

21001122111209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001122111209 is an equidigital number, since it uses as much as digits as its factorization.

21001122111209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 23.

The spelling of 21001122111209 in words is "twenty-one trillion, one billion, one hundred twenty-two million, one hundred eleven thousand, two hundred nine".