81541309 has 4 divisors (see below), whose sum is σ = 81851616. Its totient is φ = 81231004.

The previous prime is 81541297. The next prime is 81541319. The reversal of 81541309 is 90314518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81541309 - 2⁵ = 81541277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81541319) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 154759 + ... + 155284.

It is an arithmetic number, because the mean of its divisors is an integer number (20462904).

Almost surely, 2^81541309 is an apocalyptic number.

It is an amenable number.

81541309 is a deficient number, since it is larger than the sum of its proper divisors (310307).

81541309 is a wasteful number, since it uses less digits than its factorization.

81541309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310306.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 81541309 is about 9030.0226467047. The cubic root of 81541309 is about 433.6365624508.

It can be divided in two parts, 815 and 41309, that added together give a palindrome (42124).

The spelling of 81541309 in words is "eighty-one million, five hundred forty-one thousand, three hundred nine".