21205234133 has 2 divisors, whose sum is σ = 21205234134. Its totient is φ = 21205234132.

The previous prime is 21205234051. The next prime is 21205234139. The reversal of 21205234133 is 33143250212.

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., 17678893444 + 3526340689 = 132962^2 + 59383^2 .

It is a cyclic number.

It is not a de Polignac number, because 21205234133 - 2¹⁰ = 21205233109 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21205234139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602617066 + 10602617067.

It is an arithmetic number, because the mean of its divisors is an integer number (10602617067).

Almost surely, 2^21205234133 is an apocalyptic number.

It is an amenable number.

21205234133 is a deficient number, since it is larger than the sum of its proper divisors (1).

21205234133 is an equidigital number, since it uses as much as digits as its factorization.

21205234133 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 26.

Adding to 21205234133 its reverse (33143250212), we get a palindrome (54348484345).

The spelling of 21205234133 in words is "twenty-one billion, two hundred five million, two hundred thirty-four thousand, one hundred thirty-three".