21560521889 has 2 divisors, whose sum is σ = 21560521890. Its totient is φ = 21560521888.

The previous prime is 21560521831. The next prime is 21560521937. The reversal of 21560521889 is 98812506512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17744371264 + 3816150625 = 133208^2 + 61775^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21560521889 is a prime.

It is a super-2 number, since 2×21560521889² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21560521819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10780260944 + 10780260945.

It is an arithmetic number, because the mean of its divisors is an integer number (10780260945).

Almost surely, 2^21560521889 is an apocalyptic number.

It is an amenable number.

21560521889 is a deficient number, since it is larger than the sum of its proper divisors (1).

21560521889 is an equidigital number, since it uses as much as digits as its factorization.

21560521889 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 345600, while the sum is 47.

The spelling of 21560521889 in words is "twenty-one billion, five hundred sixty million, five hundred twenty-one thousand, eight hundred eighty-nine".