81693644029 has 2 divisors, whose sum is σ = 81693644030. Its totient is φ = 81693644028.

The previous prime is 81693643991. The next prime is 81693644059. The reversal of 81693644029 is 92044639618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72989127225 + 8704516804 = 270165^2 + 93298^2 .

It is a cyclic number.

It is not a de Polignac number, because 81693644029 - 2²¹ = 81691546877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81693644059) 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, 40846822014 + 40846822015.

It is an arithmetic number, because the mean of its divisors is an integer number (40846822015).

Almost surely, 2^81693644029 is an apocalyptic number.

It is an amenable number.

81693644029 is a deficient number, since it is larger than the sum of its proper divisors (1).

81693644029 is an equidigital number, since it uses as much as digits as its factorization.

81693644029 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2239488, while the sum is 52.

The spelling of 81693644029 in words is "eighty-one billion, six hundred ninety-three million, six hundred forty-four thousand, twenty-nine".