81365749 has 2 divisors, whose sum is σ = 81365750. Its totient is φ = 81365748.

The previous prime is 81365741. The next prime is 81365773. The reversal of 81365749 is 94756318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77563249 + 3802500 = 8807^2 + 1950^2 .

It is a cyclic number.

It is not a de Polignac number, because 81365749 - 2³ = 81365741 is a prime.

It is a super-2 number, since 2×81365749² = 13240770220662002, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81365741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40682874 + 40682875.

It is an arithmetic number, because the mean of its divisors is an integer number (40682875).

Almost surely, 2^81365749 is an apocalyptic number.

It is an amenable number.

81365749 is a deficient number, since it is larger than the sum of its proper divisors (1).

81365749 is an equidigital number, since it uses as much as digits as its factorization.

81365749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 43.

The square root of 81365749 is about 9020.2965028873. The cubic root of 81365749 is about 433.3251295620.

The spelling of 81365749 in words is "eighty-one million, three hundred sixty-five thousand, seven hundred forty-nine".