81675857 has 4 divisors (see below), whose sum is σ = 81742500. Its totient is φ = 81609216.

The previous prime is 81675833. The next prime is 81675929. The reversal of 81675857 is 75857618.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75857618 = 2 ⋅37928809.

It can be written as a sum of positive squares in 2 ways, for example, as 21520321 + 60155536 = 4639^2 + 7756^2 .

It is a cyclic number.

It is not a de Polignac number, because 81675857 - 2¹⁰ = 81674833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81675817) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 31448 + ... + 33945.

It is an arithmetic number, because the mean of its divisors is an integer number (20435625).

Almost surely, 2^81675857 is an apocalyptic number.

It is an amenable number.

81675857 is a deficient number, since it is larger than the sum of its proper divisors (66643).

81675857 is a wasteful number, since it uses less digits than its factorization.

81675857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66642.

The product of its digits is 470400, while the sum is 47.

The square root of 81675857 is about 9037.4696126737. The cubic root of 81675857 is about 433.8749400757.

The spelling of 81675857 in words is "eighty-one million, six hundred seventy-five thousand, eight hundred fifty-seven".