21064643807 has 2 divisors, whose sum is σ = 21064643808. Its totient is φ = 21064643806.

The previous prime is 21064643779. The next prime is 21064643837. The reversal of 21064643807 is 70834646012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21064643807 - 2²² = 21060449503 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21064643837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10532321903 + 10532321904.

It is an arithmetic number, because the mean of its divisors is an integer number (10532321904).

Almost surely, 2^21064643807 is an apocalyptic number.

21064643807 is a deficient number, since it is larger than the sum of its proper divisors (1).

21064643807 is an equidigital number, since it uses as much as digits as its factorization.

21064643807 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 193536, while the sum is 41.

The spelling of 21064643807 in words is "twenty-one billion, sixty-four million, six hundred forty-three thousand, eight hundred seven".