1291931 has 2 divisors, whose sum is σ = 1291932. Its totient is φ = 1291930.

The previous prime is 1291909. The next prime is 1291957. The reversal of 1291931 is 1391921.

It is an a-pointer prime, because the next prime (1291957) can be obtained adding 1291931 to its sum of digits (26).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1291931 - 2¹⁰ = 1290907 is a prime.

It is a super-2 number, since 2×1291931² = 3338171417522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1291931.

It is not a weakly prime, because it can be changed into another prime (1291991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645965 + 645966.

It is an arithmetic number, because the mean of its divisors is an integer number (645966).

2^1291931 is an apocalyptic number.

1291931 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291931 is an equidigital number, since it uses as much as digits as its factorization.

1291931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 486, while the sum is 26.

The square root of 1291931 is about 1136.6314266287. The cubic root of 1291931 is about 108.9130131117.

It can be divided in two parts, 1291 and 931, that added together give a palindrome (2222).

The spelling of 1291931 in words is "one million, two hundred ninety-one thousand, nine hundred thirty-one".