218491 has 12 divisors (see below), whose sum is σ = 274512. Its totient is φ = 172872.

The previous prime is 218479. The next prime is 218509. The reversal of 218491 is 194812.

It is a happy number.

It is not a de Polignac number, because 218491 - 2⁵ = 218459 is a prime.

Its product of digits (576) is a multiple of the sum of its prime factors (48).

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (218401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16801 + ... + 16813.

It is an arithmetic number, because the mean of its divisors is an integer number (22876).

218491 is a Friedman number, since it can be written as 91*(8-2+1)^4, using all its digits and the basic arithmetic operations.

2²¹⁸⁴⁹¹ is an apocalyptic number.

218491 is a deficient number, since it is larger than the sum of its proper divisors (56021).

218491 is an frugal number, since it uses more digits than its factorization.

218491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48 (or 20 counting only the distinct ones).

The product of its digits is 576, while the sum is 25.

The square root of 218491 is about 467.4302086943. The cubic root of 218491 is about 60.2297671427.

The spelling of 218491 in words is "two hundred eighteen thousand, four hundred ninety-one".