1931 has 2 divisors, whose sum is σ = 1932. Its totient is φ = 1930.

The previous prime is 1913. The next prime is 1933. The reversal of 1931 is 1391.

Together with previous prime (1913) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1931 - 2^{6} = 1867 is a prime.

It is a super-2 number, since 2×1931^{2} = 7457522, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 1933, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 12, base 14, base 15 and base 16.

It is an inconsummate number, since it does not exist a number *n* which divided by its sum of digits gives 1931.

It is not a weakly prime, because it can be changed into another prime (1933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 965 + 966.

It is an arithmetic number, because the mean of its divisors is an integer number (966).

1931 is a deficient number, since it is larger than the sum of its proper divisors (1).

1931 is an equidigital number, since it uses as much as digits as its factorization.

1931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27, while the sum is 14.

The square root of 1931 is about 43.9431450854. The cubic root of 1931 is about 12.4526206426.

The spelling of 1931 in words is "one thousand, nine hundred thirty-one".

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