81293185 has 8 divisors (see below), whose sum is σ = 97647336. Its totient is φ = 64970880.

The previous prime is 81293161. The next prime is 81293237. The reversal of 81293185 is 58139218.

It can be written as a sum of positive squares in 4 ways, for example, as 2598544 + 78694641 = 1612^2 + 8871^2 .

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

It is not a de Polignac number, because 81293185 - 2⁷ = 81293057 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1926 + ... + 12895.

It is an arithmetic number, because the mean of its divisors is an integer number (12205917).

Almost surely, 2^81293185 is an apocalyptic number.

It is an amenable number.

81293185 is a deficient number, since it is larger than the sum of its proper divisors (16354151).

81293185 is a wasteful number, since it uses less digits than its factorization.

81293185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15923.

The product of its digits is 17280, while the sum is 37.

The square root of 81293185 is about 9016.2733432389. The cubic root of 81293185 is about 433.1962745373.

The spelling of 81293185 in words is "eighty-one million, two hundred ninety-three thousand, one hundred eighty-five".