81368851 has 4 divisors (see below), whose sum is σ = 86155272. Its totient is φ = 76582432.

The previous prime is 81368843. The next prime is 81368869. The reversal of 81368851 is 15886318.

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

It is a cyclic number.

It is not a de Polignac number, because 81368851 - 2³ = 81368843 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81369851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2393185 + ... + 2393218.

It is an arithmetic number, because the mean of its divisors is an integer number (21538818).

Almost surely, 2^81368851 is an apocalyptic number.

81368851 is a deficient number, since it is larger than the sum of its proper divisors (4786421).

81368851 is a wasteful number, since it uses less digits than its factorization.

81368851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4786420.

The product of its digits is 46080, while the sum is 40.

The square root of 81368851 is about 9020.4684468158. The cubic root of 81368851 is about 433.3306362094.

The spelling of 81368851 in words is "eighty-one million, three hundred sixty-eight thousand, eight hundred fifty-one".