81783 has 16 divisors (see below), whose sum is σ = 131040. Its totient is φ = 50112.

The previous prime is 81773. The next prime is 81799. The reversal of 81783 is 38718.

81783 is nontrivially palindromic in base 12.

It is not a de Polignac number, because 81783 - 2⁸ = 81527 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

81783 is an undulating number in base 12.

81783 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81703) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 235 + ... + 467.

It is an arithmetic number, because the mean of its divisors is an integer number (8190).

2⁸¹⁷⁸³ is an apocalyptic number.

81783 is a deficient number, since it is larger than the sum of its proper divisors (49257).

81783 is a wasteful number, since it uses less digits than its factorization.

81783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255 (or 249 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 81783 is about 285.9772718242. The cubic root of 81783 is about 43.4064577308.

Adding to 81783 its sum of digits (27), we get a triangular number (81810 = T₄₀₄).

It can be divided in two parts, 817 and 83, that added together give a square (900 = 30²).

The spelling of 81783 in words is "eighty-one thousand, seven hundred eighty-three".