521866799989 has 2 divisors, whose sum is σ = 521866799990. Its totient is φ = 521866799988.

The previous prime is 521866799947. The next prime is 521866800029. The reversal of 521866799989 is 989997668125.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 500332704964 + 21534095025 = 707342^2 + 146745^2 .

It is a cyclic number.

It is not a de Polignac number, because 521866799989 - 2²¹ = 521864702837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521866793989) 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, 260933399994 + 260933399995.

It is an arithmetic number, because the mean of its divisors is an integer number (260933399995).

Almost surely, 2^521866799989 is an apocalyptic number.

It is an amenable number.

521866799989 is a deficient number, since it is larger than the sum of its proper divisors (1).

521866799989 is an equidigital number, since it uses as much as digits as its factorization.

521866799989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1058158080, while the sum is 79.

The spelling of 521866799989 in words is "five hundred twenty-one billion, eight hundred sixty-six million, seven hundred ninety-nine thousand, nine hundred eighty-nine".