81916812 has 48 divisors (see below), whose sum is σ = 224874720. Its totient is φ = 25698816.

The previous prime is 81916781. The next prime is 81916819. The reversal of 81916812 is 21861918.

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

It is not an unprimeable number, because it can be changed into a prime (81916819) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20473 + ... + 24144.

It is an arithmetic number, because the mean of its divisors is an integer number (4684890).

Almost surely, 2^81916812 is an apocalyptic number.

It is an amenable number.

81916812 is an abundant number, since it is smaller than the sum of its proper divisors (142957908).

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

81916812 is a wasteful number, since it uses less digits than its factorization.

81916812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44647 (or 44639 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 81916812 is about 9050.7906836917. The cubic root of 81916812 is about 434.3011847518.

It can be divided in two parts, 81916 and 812, that added together give a palindrome (82728).

The spelling of 81916812 in words is "eighty-one million, nine hundred sixteen thousand, eight hundred twelve".