221831 has 2 divisors, whose sum is σ = 221832. Its totient is φ = 221830.

The previous prime is 221827. The next prime is 221849. The reversal of 221831 is 138122.

221831 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221831 - 2² = 221827 is a prime.

It is a super-2 number, since 2×221831² = 98417985122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110915 + 110916.

It is an arithmetic number, because the mean of its divisors is an integer number (110916).

2²²¹⁸³¹ is an apocalyptic number.

221831 is a deficient number, since it is larger than the sum of its proper divisors (1).

221831 is an equidigital number, since it uses as much as digits as its factorization.

221831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96, while the sum is 17.

The square root of 221831 is about 470.9893841691. The cubic root of 221831 is about 60.5351206506.

Adding to 221831 its reverse (138122), we get a palindrome (359953).

The spelling of 221831 in words is "two hundred twenty-one thousand, eight hundred thirty-one".