1311681 has 12 divisors (see below), whose sum is σ = 2034672. Its totient is φ = 749448.

The previous prime is 1311643. The next prime is 1311689. The reversal of 1311681 is 1861131.

1311681 = 139² + 140² + ... + 187².

It is not a de Polignac number, because 1311681 - 2⁶ = 1311617 is a prime.

It is a super-2 number, since 2×1311681² = 3441014091522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (1311689) 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 in 11 ways as a sum of consecutive naturals, for example, 4315 + ... + 4608.

It is an arithmetic number, because the mean of its divisors is an integer number (169556).

2^1311681 is an apocalyptic number.

It is an amenable number.

1311681 is a deficient number, since it is larger than the sum of its proper divisors (722991).

1311681 is an equidigital number, since it uses as much as digits as its factorization.

1311681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8940 (or 8933 counting only the distinct ones).

The product of its digits is 144, while the sum is 21.

The square root of 1311681 is about 1145.2864270566. The cubic root of 1311681 is about 109.4652002591.

The spelling of 1311681 in words is "one million, three hundred eleven thousand, six hundred eighty-one".