81663 has 8 divisors (see below), whose sum is σ = 110208. Its totient is φ = 53784.

The previous prime is 81649. The next prime is 81667. The reversal of 81663 is 36618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81663 - 2⁴ = 81647 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81663.

It is not an unprimeable number, because it can be changed into a prime (81667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 406 + ... + 572.

It is an arithmetic number, because the mean of its divisors is an integer number (13776).

2⁸¹⁶⁶³ is an apocalyptic number.

81663 is a deficient number, since it is larger than the sum of its proper divisors (28545).

81663 is a wasteful number, since it uses less digits than its factorization.

81663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333.

The product of its digits is 864, while the sum is 24.

The square root of 81663 is about 285.7673879224. The cubic root of 81663 is about 43.3852172749.

The spelling of 81663 in words is "eighty-one thousand, six hundred sixty-three".