81584761 has 4 divisors (see below), whose sum is σ = 82802512. Its totient is φ = 80367012.

The previous prime is 81584753. The next prime is 81584771. The reversal of 81584761 is 16748518.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16748518 = 2 ⋅8374259.

It is a cyclic number.

It is not a de Polignac number, because 81584761 - 2³ = 81584753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81584771) 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, 608775 + ... + 608908.

It is an arithmetic number, because the mean of its divisors is an integer number (20700628).

Almost surely, 2^81584761 is an apocalyptic number.

It is an amenable number.

81584761 is a deficient number, since it is larger than the sum of its proper divisors (1217751).

81584761 is a wasteful number, since it uses less digits than its factorization.

81584761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1217750.

The product of its digits is 53760, while the sum is 40.

The square root of 81584761 is about 9032.4283002967. The cubic root of 81584761 is about 433.7135746638.

The spelling of 81584761 in words is "eighty-one million, five hundred eighty-four thousand, seven hundred sixty-one".