81683712 has 162 divisors, whose sum is σ = 259754586. Its totient is φ = 24668160.

The previous prime is 81683711. The next prime is 81683731. The reversal of 81683712 is 21738618.

It can be written as a sum of positive squares in only one way, i.e., 80568576 + 1115136 = 8976^2 + 1056^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81683711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 278638 + ... + 278930.

Almost surely, 2^81683712 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 81683712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129877293).

81683712 is an abundant number, since it is smaller than the sum of its proper divisors (178070874).

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

81683712 is a wasteful number, since it uses less digits than its factorization.

81683712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337 (or 309 counting only the distinct ones).

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

The square root of 81683712 is about 9037.9041818333. The cubic root of 81683712 is about 433.8888486264. Note that the first 4 decimals are identical.

The spelling of 81683712 in words is "eighty-one million, six hundred eighty-three thousand, seven hundred twelve".