81349765 has 32 divisors (see below), whose sum is σ = 115163136. Its totient is φ = 54008640.

The previous prime is 81349739. The next prime is 81349769. The reversal of 81349765 is 56794318.

It is not a de Polignac number, because 81349765 - 2⁵ = 81349733 is a prime.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81349769) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 287314 + ... + 287596.

It is an arithmetic number, because the mean of its divisors is an integer number (3598848).

Almost surely, 2^81349765 is an apocalyptic number.

It is an amenable number.

81349765 is a deficient number, since it is larger than the sum of its proper divisors (33813371).

81349765 is a wasteful number, since it uses less digits than its factorization.

81349765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 529.

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

The square root of 81349765 is about 9019.4104574523. The cubic root of 81349765 is about 433.2967526649.

The spelling of 81349765 in words is "eighty-one million, three hundred forty-nine thousand, seven hundred sixty-five".