181663 has 4 divisors (see below), whose sum is σ = 182520. Its totient is φ = 180808.

The previous prime is 181639. The next prime is 181667. The reversal of 181663 is 366181.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 181663 - 2¹⁷ = 50591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181667) 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 3 ways as a sum of consecutive naturals, for example, 156 + ... + 622.

It is an arithmetic number, because the mean of its divisors is an integer number (45630).

2¹⁸¹⁶⁶³ is an apocalyptic number.

181663 is a deficient number, since it is larger than the sum of its proper divisors (857).

181663 is an equidigital number, since it uses as much as digits as its factorization.

181663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 856.

The product of its digits is 864, while the sum is 25.

The square root of 181663 is about 426.2194270561. The cubic root of 181663 is about 56.6355115170.

It can be divided in two parts, 18 and 1663, that added together give a square (1681 = 41²).

The spelling of 181663 in words is "one hundred eighty-one thousand, six hundred sixty-three".