221618231 has 2 divisors, whose sum is σ = 221618232. Its totient is φ = 221618230.

The previous prime is 221618167. The next prime is 221618249. The reversal of 221618231 is 132816122.

221618231 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221618231 - 2⁶ = 221618167 is a prime.

It is a super-2 number, since 2×221618231² = 98229280623138722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221618231.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221614231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110809115 + 110809116.

It is an arithmetic number, because the mean of its divisors is an integer number (110809116).

Almost surely, 2^221618231 is an apocalyptic number.

221618231 is a deficient number, since it is larger than the sum of its proper divisors (1).

221618231 is an equidigital number, since it uses as much as digits as its factorization.

221618231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 26.

The square root of 221618231 is about 14886.8475843612. The cubic root of 221618231 is about 605.1576039099.

The spelling of 221618231 in words is "two hundred twenty-one million, six hundred eighteen thousand, two hundred thirty-one".