81749 has 2 divisors, whose sum is σ = 81750. Its totient is φ = 81748.

The previous prime is 81737. The next prime is 81761. The reversal of 81749 is 94718.

It is a balanced prime because it is at equal distance from previous prime (81737) and next prime (81761).

It can be written as a sum of positive squares in only one way, i.e., 47524 + 34225 = 218^2 + 185^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81749 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40874 + 40875.

It is an arithmetic number, because the mean of its divisors is an integer number (40875).

2⁸¹⁷⁴⁹ is an apocalyptic number.

It is an amenable number.

81749 is a deficient number, since it is larger than the sum of its proper divisors (1).

81749 is an equidigital number, since it uses as much as digits as its factorization.

81749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 81749 is about 285.9178203610. The cubic root of 81749 is about 43.4004417123.

The spelling of 81749 in words is "eighty-one thousand, seven hundred forty-nine".