81318956 has 24 divisors (see below), whose sum is σ = 151534656. Its totient is φ = 38050560.

The previous prime is 81318947. The next prime is 81318959. The reversal of 81318956 is 65981318.

It is a super-2 number, since 2×81318956² = 13225545209859872, which contains 22 as substring.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (81318959) 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, 9005 + ... + 15611.

It is an arithmetic number, because the mean of its divisors is an integer number (6313944).

Almost surely, 2^81318956 is an apocalyptic number.

It is an amenable number.

81318956 is a deficient number, since it is larger than the sum of its proper divisors (70215700).

81318956 is a wasteful number, since it uses less digits than its factorization.

81318956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6809 (or 6807 counting only the distinct ones).

The product of its digits is 51840, while the sum is 41.

The square root of 81318956 is about 9017.7023681202. The cubic root of 81318956 is about 433.2420459907.

The spelling of 81318956 in words is "eighty-one million, three hundred eighteen thousand, nine hundred fifty-six".