81316872 has 240 divisors, whose sum is σ = 286777260. Its totient is φ = 21337344.

The previous prime is 81316871. The next prime is 81316877. The reversal of 81316872 is 27861318.

It can be written as a sum of positive squares in 2 ways, for example, as 80030916 + 1285956 = 8946^2 + 1134^2 .

It is a super-2 number, since 2×81316872² = 13224867343728768, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (81316871) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 412678 + ... + 412874.

Almost surely, 2^81316872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81316872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143388630).

81316872 is an abundant number, since it is smaller than the sum of its proper divisors (205460388).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81316872 is a wasteful number, since it uses less digits than its factorization.

81316872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242 (or 222 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 81316872 is about 9017.5868168818. The cubic root of 81316872 is about 433.2383449917.

The spelling of 81316872 in words is "eighty-one million, three hundred sixteen thousand, eight hundred seventy-two".