81684372 has 144 divisors (see below), whose sum is σ = 246601152. Its totient is φ = 20805120.

The previous prime is 81684359. The next prime is 81684373. The reversal of 81684372 is 27348618.

It is a self number, because there is not a number n which added to its sum of digits gives 81684372.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81684373) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 472078 + ... + 472250.

It is an arithmetic number, because the mean of its divisors is an integer number (1712508).

Almost surely, 2^81684372 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 81684372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123300576).

81684372 is an abundant number, since it is smaller than the sum of its proper divisors (164916780).

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

81684372 is a wasteful number, since it uses less digits than its factorization.

81684372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278 (or 269 counting only the distinct ones).

The product of its digits is 64512, while the sum is 39.

The square root of 81684372 is about 9037.9406946494. The cubic root of 81684372 is about 433.8900172228.

The spelling of 81684372 in words is "eighty-one million, six hundred eighty-four thousand, three hundred seventy-two".