181638 has 12 divisors (see below), whose sum is σ = 393588. Its totient is φ = 60540.

The previous prime is 181619. The next prime is 181639. The reversal of 181638 is 836181.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181639) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5028 + ... + 5063.

It is an arithmetic number, because the mean of its divisors is an integer number (32799).

2¹⁸¹⁶³⁸ is an apocalyptic number.

181638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

181638 is an abundant number, since it is smaller than the sum of its proper divisors (211950).

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

181638 is a wasteful number, since it uses less digits than its factorization.

181638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10099 (or 10096 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 181638 is about 426.1900984303. The cubic root of 181638 is about 56.6329133861.

The spelling of 181638 in words is "one hundred eighty-one thousand, six hundred thirty-eight".