766321999981 has 2 divisors, whose sum is σ = 766321999982. Its totient is φ = 766321999980.

The previous prime is 766321999931. The next prime is 766322000009. The reversal of 766321999981 is 189999123667.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 600212770756 + 166109229225 = 774734^2 + 407565^2 .

It is a cyclic number.

It is not a de Polignac number, because 766321999981 - 2⁷ = 766321999853 is a prime.

It is a super-2 number, since 2×766321999981² (a number of 25 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 766321999981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (766321999901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 383160999990 + 383160999991.

It is an arithmetic number, because the mean of its divisors is an integer number (383160999991).

Almost surely, 2^766321999981 is an apocalyptic number.

It is an amenable number.

766321999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

766321999981 is an equidigital number, since it uses as much as digits as its factorization.

766321999981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 79361856, while the sum is 70.

The spelling of 766321999981 in words is "seven hundred sixty-six billion, three hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred eighty-one".