81683540 has 12 divisors (see below), whose sum is σ = 171535476. Its totient is φ = 32673408.

The previous prime is 81683501. The next prime is 81683587. The reversal of 81683540 is 4538618.

It can be written as a sum of positive squares in 2 ways, for example, as 36336784 + 45346756 = 6028^2 + 6734^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81683540.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2042069 + ... + 2042108.

It is an arithmetic number, because the mean of its divisors is an integer number (14294623).

Almost surely, 2^81683540 is an apocalyptic number.

It is an amenable number.

81683540 is an abundant number, since it is smaller than the sum of its proper divisors (89851936).

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

81683540 is a wasteful number, since it uses less digits than its factorization.

81683540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4084186 (or 4084184 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 81683540 is about 9037.8946663479. The cubic root of 81683540 is about 433.8885440821. Note that the first 3 decimals are identical.

The spelling of 81683540 in words is "eighty-one million, six hundred eighty-three thousand, five hundred forty".