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1231 is a prime number

1231 has 2 divisors, whose sum is σ = 1232. Its totient is φ = 1230.

The previous prime is 1229. The next prime is 1237. The reversal of 1231 is 1321.

Adding to 1231 its reverse (1321), we get a palindrome (2552).

It can be divided in two parts, 1 and 231, that added together give a palindrome (232).

1231 is nontrivially palindromic in base 11.

It is a m-pointer prime, because the next prime (1237) can be obtained adding 1231 to its product of digits (6).

It is a weak prime.

It is an emirp because it is prime and its reverse (1321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1231 - 21 = 1229 is a prime.

It is a super-2 number, since 2×12312 = 3030722, which contains 22 as substring.

Together with 1229, it forms a pair of twin primes.

1231 is an undulating number in base 11.

1231 is a lucky number.

It is a plaindrome in base 16.

It is a nialpdrome in base 6.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1237) by changing a digit.


It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615 + 616.

It is an arithmetic number, because the mean of its divisors is an integer number (616).


1231 is an equidigital number, since it uses as much as digits as its factorization.

1231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6, while the sum is 7.

The square root of 1231 is about 35.0856095857. The cubic root of 1231 is about 10.7173155452.

The spelling of 1231 in words is "one thousand, two hundred thirty-one".