21147945647 has 2 divisors, whose sum is σ = 21147945648. Its totient is φ = 21147945646.

The previous prime is 21147945641. The next prime is 21147945661. The reversal of 21147945647 is 74654974112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21147945647 - 2¹⁸ = 21147683503 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21147945595 and 21147945604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21147945641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10573972823 + 10573972824.

It is an arithmetic number, because the mean of its divisors is an integer number (10573972824).

Almost surely, 2^21147945647 is an apocalyptic number.

21147945647 is a deficient number, since it is larger than the sum of its proper divisors (1).

21147945647 is an equidigital number, since it uses as much as digits as its factorization.

21147945647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1693440, while the sum is 50.

The spelling of 21147945647 in words is "twenty-one billion, one hundred forty-seven million, nine hundred forty-five thousand, six hundred forty-seven".