993788681 has 2 divisors, whose sum is σ = 993788682. Its totient is φ = 993788680.

The previous prime is 993788659. The next prime is 993788683. The reversal of 993788681 is 186887399.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 847741456 + 146047225 = 29116^2 + 12085^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-993788681 is a prime.

It is a super-2 number, since 2×993788681² = 1975231884967439522, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 993788683, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 993788681.

It is not a weakly prime, because it can be changed into another prime (993788683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 496894340 + 496894341.

It is an arithmetic number, because the mean of its divisors is an integer number (496894341).

Almost surely, 2^993788681 is an apocalyptic number.

It is an amenable number.

993788681 is a deficient number, since it is larger than the sum of its proper divisors (1).

993788681 is an equidigital number, since it uses as much as digits as its factorization.

993788681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5225472, while the sum is 59.

The square root of 993788681 is about 31524.4140468939. The cubic root of 993788681 is about 997.9252587591.

The spelling of 993788681 in words is "nine hundred ninety-three million, seven hundred eighty-eight thousand, six hundred eighty-one".