21644485859 has 2 divisors, whose sum is σ = 21644485860. Its totient is φ = 21644485858.

The previous prime is 21644485843. The next prime is 21644485871. The reversal of 21644485859 is 95858444612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21644485859 - 2⁴ = 21644485843 is a prime.

It is not a weakly prime, because it can be changed into another prime (21644485829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10822242929 + 10822242930.

It is an arithmetic number, because the mean of its divisors is an integer number (10822242930).

Almost surely, 2^21644485859 is an apocalyptic number.

21644485859 is a deficient number, since it is larger than the sum of its proper divisors (1).

21644485859 is an equidigital number, since it uses as much as digits as its factorization.

21644485859 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11059200, while the sum is 56.

The spelling of 21644485859 in words is "twenty-one billion, six hundred forty-four million, four hundred eighty-five thousand, eight hundred fifty-nine".