81157583 has 4 divisors (see below), whose sum is σ = 87400488. Its totient is φ = 74914680.

The previous prime is 81157543. The next prime is 81157589. The reversal of 81157583 is 38575118.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81157583 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 (81157589) 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 3 ways as a sum of consecutive naturals, for example, 3121433 + ... + 3121458.

It is an arithmetic number, because the mean of its divisors is an integer number (21850122).

Almost surely, 2^81157583 is an apocalyptic number.

81157583 is a deficient number, since it is larger than the sum of its proper divisors (6242905).

81157583 is a wasteful number, since it uses less digits than its factorization.

81157583 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6242904.

The product of its digits is 33600, while the sum is 38.

The square root of 81157583 is about 9008.7503572915. The cubic root of 81157583 is about 432.9552745345.

The spelling of 81157583 in words is "eighty-one million, one hundred fifty-seven thousand, five hundred eighty-three".