81683574 has 64 divisors (see below), whose sum is σ = 197345280. Its totient is φ = 22044960.

The previous prime is 81683501. The next prime is 81683587. The reversal of 81683574 is 47538618.

It is a super-2 number, since 2×81683574² = 13344412522826952, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 55257 + ... + 56715.

It is an arithmetic number, because the mean of its divisors is an integer number (3083520).

Almost surely, 2^81683574 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81683574, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (98672640).

81683574 is an abundant number, since it is smaller than the sum of its proper divisors (115661706).

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

81683574 is a wasteful number, since it uses less digits than its factorization.

81683574 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1545.

The product of its digits is 161280, while the sum is 42.

The square root of 81683574 is about 9037.8965473167. The cubic root of 81683574 is about 433.8886042828. Note that the first 3 decimals are identical.

The spelling of 81683574 in words is "eighty-one million, six hundred eighty-three thousand, five hundred seventy-four".