21255243102647 has 2 divisors, whose sum is σ = 21255243102648. Its totient is φ = 21255243102646.

The previous prime is 21255243102629. The next prime is 21255243102689. The reversal of 21255243102647 is 74620134255212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21255243102647 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21255243102598 and 21255243102607.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255243101647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627621551323 + 10627621551324.

It is an arithmetic number, because the mean of its divisors is an integer number (10627621551324).

Almost surely, 2^{21255243102647} is an apocalyptic number.

21255243102647 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255243102647 is an equidigital number, since it uses as much as digits as its factorization.

21255243102647 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 806400, while the sum is 44.

Adding to 21255243102647 its reverse (74620134255212), we get a palindrome (95875377357859).

The spelling of 21255243102647 in words is "twenty-one trillion, two hundred fifty-five billion, two hundred forty-three million, one hundred two thousand, six hundred forty-seven".