21201221051 has 2 divisors, whose sum is σ = 21201221052. Its totient is φ = 21201221050.

The previous prime is 21201221021. The next prime is 21201221057. The reversal of 21201221051 is 15012210212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21201221051 - 2²⁶ = 21134112187 is a prime.

It is not a weakly prime, because it can be changed into another prime (21201221057) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600610525 + 10600610526.

It is an arithmetic number, because the mean of its divisors is an integer number (10600610526).

Almost surely, 2^21201221051 is an apocalyptic number.

21201221051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201221051 is an equidigital number, since it uses as much as digits as its factorization.

21201221051 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80, while the sum is 17.

Adding to 21201221051 its reverse (15012210212), we get a palindrome (36213431263).

The spelling of 21201221051 in words is "twenty-one billion, two hundred one million, two hundred twenty-one thousand, fifty-one".