21205234051 has 2 divisors, whose sum is σ = 21205234052. Its totient is φ = 21205234050.

The previous prime is 21205233997. The next prime is 21205234133. The reversal of 21205234051 is 15043250212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21205234051 - 2²³ = 21196845443 is a prime.

It is not a weakly prime, because it can be changed into another prime (21205234151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602617025 + 10602617026.

It is an arithmetic number, because the mean of its divisors is an integer number (10602617026).

Almost surely, 2^21205234051 is an apocalyptic number.

21205234051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21205234051 is an equidigital number, since it uses as much as digits as its factorization.

21205234051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2400, while the sum is 25.

Adding to 21205234051 its reverse (15043250212), we get a palindrome (36248484263).

The spelling of 21205234051 in words is "twenty-one billion, two hundred five million, two hundred thirty-four thousand, fifty-one".