21188563889 has 2 divisors, whose sum is σ = 21188563890. Its totient is φ = 21188563888.

The previous prime is 21188563883. The next prime is 21188563897. The reversal of 21188563889 is 98836588112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16820014864 + 4368549025 = 129692^2 + 66095^2 .

It is a cyclic number.

It is not a de Polignac number, because 21188563889 - 2¹² = 21188559793 is a prime.

It is not a weakly prime, because it can be changed into another prime (21188563883) 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, 10594281944 + 10594281945.

It is an arithmetic number, because the mean of its divisors is an integer number (10594281945).

Almost surely, 2^21188563889 is an apocalyptic number.

It is an amenable number.

21188563889 is a deficient number, since it is larger than the sum of its proper divisors (1).

21188563889 is an equidigital number, since it uses as much as digits as its factorization.

21188563889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6635520, while the sum is 59.

The spelling of 21188563889 in words is "twenty-one billion, one hundred eighty-eight million, five hundred sixty-three thousand, eight hundred eighty-nine".