21243263647 has 2 divisors, whose sum is σ = 21243263648. Its totient is φ = 21243263646.

The previous prime is 21243263533. The next prime is 21243263669. The reversal of 21243263647 is 74636234212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21243263647 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21243263147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621631823 + 10621631824.

It is an arithmetic number, because the mean of its divisors is an integer number (10621631824).

Almost surely, 2^21243263647 is an apocalyptic number.

21243263647 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243263647 is an equidigital number, since it uses as much as digits as its factorization.

21243263647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 40.

Adding to 21243263647 its reverse (74636234212), we get a palindrome (95879497859).

The spelling of 21243263647 in words is "twenty-one billion, two hundred forty-three million, two hundred sixty-three thousand, six hundred forty-seven".