81340746749 has 2 divisors, whose sum is σ = 81340746750. Its totient is φ = 81340746748.

The previous prime is 81340746743. The next prime is 81340746769. The reversal of 81340746749 is 94764704318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74248075225 + 7092671524 = 272485^2 + 84218^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81340746749 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81340746749.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81340746743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40670373374 + 40670373375.

It is an arithmetic number, because the mean of its divisors is an integer number (40670373375).

Almost surely, 2^81340746749 is an apocalyptic number.

It is an amenable number.

81340746749 is a deficient number, since it is larger than the sum of its proper divisors (1).

81340746749 is an equidigital number, since it uses as much as digits as its factorization.

81340746749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4064256, while the sum is 53.

The spelling of 81340746749 in words is "eighty-one billion, three hundred forty million, seven hundred forty-six thousand, seven hundred forty-nine".