21651260263 has 2 divisors, whose sum is σ = 21651260264. Its totient is φ = 21651260262.

The previous prime is 21651260261. The next prime is 21651260269. The reversal of 21651260263 is 36206215612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21651260263 - 2¹ = 21651260261 is a prime.

Together with 21651260261, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21651260261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10825630131 + 10825630132.

It is an arithmetic number, because the mean of its divisors is an integer number (10825630132).

Almost surely, 2^21651260263 is an apocalyptic number.

21651260263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21651260263 is an equidigital number, since it uses as much as digits as its factorization.

21651260263 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 34.

Adding to 21651260263 its reverse (36206215612), we get a palindrome (57857475875).

The spelling of 21651260263 in words is "twenty-one billion, six hundred fifty-one million, two hundred sixty thousand, two hundred sixty-three".