21456252647 has 2 divisors, whose sum is σ = 21456252648. Its totient is φ = 21456252646.

The previous prime is 21456252589. The next prime is 21456252689. The reversal of 21456252647 is 74625265412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21456252647 - 2¹⁰ = 21456251623 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21456252598 and 21456252607.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21456252547) 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, 10728126323 + 10728126324.

It is an arithmetic number, because the mean of its divisors is an integer number (10728126324).

Almost surely, 2^21456252647 is an apocalyptic number.

21456252647 is a deficient number, since it is larger than the sum of its proper divisors (1).

21456252647 is an equidigital number, since it uses as much as digits as its factorization.

21456252647 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 21456252647 in words is "twenty-one billion, four hundred fifty-six million, two hundred fifty-two thousand, six hundred forty-seven".