1291831 has 2 divisors, whose sum is σ = 1291832. Its totient is φ = 1291830.

The previous prime is 1291819. The next prime is 1291861. The reversal of 1291831 is 1381921.

It is a weak prime.

It is an emirp because it is prime and its reverse (1381921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1291831 - 2⁵ = 1291799 is a prime.

It is a super-2 number, since 2×1291831² = 3337654665122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1291796 and 1291805.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291861) 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, 645915 + 645916.

It is an arithmetic number, because the mean of its divisors is an integer number (645916).

2^1291831 is an apocalyptic number.

1291831 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291831 is an equidigital number, since it uses as much as digits as its factorization.

1291831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 25.

The square root of 1291831 is about 1136.5874361438. The cubic root of 1291831 is about 108.9102029559.

The spelling of 1291831 in words is "one million, two hundred ninety-one thousand, eight hundred thirty-one".