8166581993 has 2 divisors, whose sum is σ = 8166581994. Its totient is φ = 8166581992.

The previous prime is 8166581987. The next prime is 8166582013. The reversal of 8166581993 is 3991856618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7010377984 + 1156204009 = 83728^2 + 34003^2 .

It is a cyclic number.

It is not a de Polignac number, because 8166581993 - 2²² = 8162387689 is a prime.

It is a super-2 number, since 2×8166581993² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (8166581393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4083290996 + 4083290997.

It is an arithmetic number, because the mean of its divisors is an integer number (4083290997).

Almost surely, 2^8166581993 is an apocalyptic number.

It is an amenable number.

8166581993 is a deficient number, since it is larger than the sum of its proper divisors (1).

8166581993 is an equidigital number, since it uses as much as digits as its factorization.

8166581993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2799360, while the sum is 56.

The square root of 8166581993 is about 90369.1429250051. The cubic root of 8166581993 is about 2013.7865794952.

The spelling of 8166581993 in words is "eight billion, one hundred sixty-six million, five hundred eighty-one thousand, nine hundred ninety-three".