216181 has 8 divisors (see below), whose sum is σ = 250560. Its totient is φ = 182688.

The previous prime is 216179. The next prime is 216211. The reversal of 216181 is 181612.

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

It is a cyclic number.

It is not a de Polignac number, because 216181 - 2¹ = 216179 is a prime.

It is a super-2 number, since 2×216181² = 93468449522, which contains 22 as substring.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216481) 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, 450 + ... + 796.

It is an arithmetic number, because the mean of its divisors is an integer number (31320).

2²¹⁶¹⁸¹ is an apocalyptic number.

It is an amenable number.

216181 is a deficient number, since it is larger than the sum of its proper divisors (34379).

216181 is an equidigital number, since it uses as much as digits as its factorization.

216181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 443.

The product of its digits is 96, while the sum is 19.

The square root of 216181 is about 464.9526857649. The cubic root of 216181 is about 60.0167545802.

Adding to 216181 its reverse (181612), we get a palindrome (397793).

The spelling of 216181 in words is "two hundred sixteen thousand, one hundred eighty-one".