221131231 has 2 divisors, whose sum is σ = 221131232. Its totient is φ = 221131230.

The previous prime is 221131219. The next prime is 221131259. The reversal of 221131231 is 132131122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221131231 - 2¹⁵ = 221098463 is a prime.

It is a super-2 number, since 2×221131231² = 97798042647150722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221131201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110565615 + 110565616.

It is an arithmetic number, because the mean of its divisors is an integer number (110565616).

Almost surely, 2^221131231 is an apocalyptic number.

221131231 is a deficient number, since it is larger than the sum of its proper divisors (1).

221131231 is an equidigital number, since it uses as much as digits as its factorization.

221131231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72, while the sum is 16.

The square root of 221131231 is about 14870.4818684534. The cubic root of 221131231 is about 604.7140063933.

Adding to 221131231 its reverse (132131122), we get a palindrome (353262353).

The spelling of 221131231 in words is "two hundred twenty-one million, one hundred thirty-one thousand, two hundred thirty-one".