81131583 has 32 divisors (see below), whose sum is σ = 120637440. Its totient is φ = 48182400.

The previous prime is 81131569. The next prime is 81131591. The reversal of 81131583 is 38513118.

It is not a de Polignac number, because 81131583 - 2⁵ = 81131551 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81131583.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81131593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 169138 + ... + 169616.

It is an arithmetic number, because the mean of its divisors is an integer number (3769920).

Almost surely, 2^81131583 is an apocalyptic number.

81131583 is a deficient number, since it is larger than the sum of its proper divisors (39505857).

81131583 is a wasteful number, since it uses less digits than its factorization.

81131583 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639.

The product of its digits is 2880, while the sum is 30.

The square root of 81131583 is about 9007.3072002680. The cubic root of 81131583 is about 432.9090351115.

The spelling of 81131583 in words is "eighty-one million, one hundred thirty-one thousand, five hundred eighty-three".