81318845 has 8 divisors (see below), whose sum is σ = 97861176. Its totient is φ = 64869376.

The previous prime is 81318833. The next prime is 81318847. The reversal of 81318845 is 54881318.

It can be written as a sum of positive squares in 4 ways, for example, as 13388281 + 67930564 = 3659^2 + 8242^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 81318845 - 2⁴ = 81318829 is a prime.

It is a super-2 number, since 2×81318845² = 13225509104268050, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81318799 and 81318808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81318847) 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, 21272 + ... + 24801.

It is an arithmetic number, because the mean of its divisors is an integer number (12232647).

Almost surely, 2^81318845 is an apocalyptic number.

It is an amenable number.

81318845 is a deficient number, since it is larger than the sum of its proper divisors (16542331).

81318845 is a wasteful number, since it uses less digits than its factorization.

81318845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46431.

The product of its digits is 30720, while the sum is 38.

The square root of 81318845 is about 9017.6962135570. The cubic root of 81318845 is about 433.2418488662.

The spelling of 81318845 in words is "eighty-one million, three hundred eighteen thousand, eight hundred forty-five".