81749674529 has 2 divisors, whose sum is σ = 81749674530. Its totient is φ = 81749674528.

The previous prime is 81749674507. The next prime is 81749674543. The reversal of 81749674529 is 92547694718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64991854225 + 16757820304 = 254935^2 + 129452^2 .

It is a cyclic number.

It is not a de Polignac number, because 81749674529 - 2²⁰ = 81748625953 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81749674549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40874837264 + 40874837265.

It is an arithmetic number, because the mean of its divisors is an integer number (40874837265).

Almost surely, 2^81749674529 is an apocalyptic number.

It is an amenable number.

81749674529 is a deficient number, since it is larger than the sum of its proper divisors (1).

81749674529 is an equidigital number, since it uses as much as digits as its factorization.

81749674529 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30481920, while the sum is 62.

The spelling of 81749674529 in words is "eighty-one billion, seven hundred forty-nine million, six hundred seventy-four thousand, five hundred twenty-nine".