21201221189 has 2 divisors, whose sum is σ = 21201221190. Its totient is φ = 21201221188.

The previous prime is 21201221177. The next prime is 21201221207. The reversal of 21201221189 is 98112210212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12241652164 + 8959569025 = 110642^2 + 94655^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201221189 - 2²⁰ = 21200172613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201221159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600610594 + 10600610595.

It is an arithmetic number, because the mean of its divisors is an integer number (10600610595).

Almost surely, 2^21201221189 is an apocalyptic number.

It is an amenable number.

21201221189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201221189 is an equidigital number, since it uses as much as digits as its factorization.

21201221189 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 29.

The spelling of 21201221189 in words is "twenty-one billion, two hundred one million, two hundred twenty-one thousand, one hundred eighty-nine".