81828591 has 8 divisors (see below), whose sum is σ = 117497520. Its totient is φ = 50356032.

The previous prime is 81828583. The next prime is 81828619. The reversal of 81828591 is 19582818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81828591 - 2³ = 81828583 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81838591) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1049046 + ... + 1049123.

It is an arithmetic number, because the mean of its divisors is an integer number (14687190).

Almost surely, 2^81828591 is an apocalyptic number.

81828591 is a deficient number, since it is larger than the sum of its proper divisors (35668929).

81828591 is a wasteful number, since it uses less digits than its factorization.

81828591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2098185.

The product of its digits is 46080, while the sum is 42.

The square root of 81828591 is about 9045.9157082078. The cubic root of 81828591 is about 434.1452206443.

The spelling of 81828591 in words is "eighty-one million, eight hundred twenty-eight thousand, five hundred ninety-one".