6660400993 has 2 divisors, whose sum is σ = 6660400994. Its totient is φ = 6660400992.

The previous prime is 6660400939. The next prime is 6660400997. The reversal of 6660400993 is 3990040666.

Together with previous prime (6660400939) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6646651729 + 13749264 = 81527^2 + 3708^2 .

It is a cyclic number.

It is not a de Polignac number, because 6660400993 - 2¹³ = 6660392801 is a prime.

It is not a weakly prime, because it can be changed into another prime (6660400997) 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, 3330200496 + 3330200497.

It is an arithmetic number, because the mean of its divisors is an integer number (3330200497).

Almost surely, 2^6660400993 is an apocalyptic number.

It is an amenable number.

6660400993 is a deficient number, since it is larger than the sum of its proper divisors (1).

6660400993 is an equidigital number, since it uses as much as digits as its factorization.

6660400993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 209952, while the sum is 43.

The square root of 6660400993 is about 81611.2798147413. The cubic root of 6660400993 is about 1881.4822504799.

The spelling of 6660400993 in words is "six billion, six hundred sixty million, four hundred thousand, nine hundred ninety-three".