1311561 has 12 divisors (see below), whose sum is σ = 1926340. Its totient is φ = 859680.

The previous prime is 1311559. The next prime is 1311577. The reversal of 1311561 is 1651131.

It can be written as a sum of positive squares in 2 ways, for example, as 145161 + 1166400 = 381^2 + 1080^2 .

It is not a de Polignac number, because 1311561 - 2¹ = 1311559 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1312561) 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, 646 + ... + 1743.

2^1311561 is an apocalyptic number.

It is an amenable number.

1311561 is a deficient number, since it is larger than the sum of its proper divisors (614779).

1311561 is a wasteful number, since it uses less digits than its factorization.

1311561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2456 (or 2453 counting only the distinct ones).

The product of its digits is 90, while the sum is 18.

The square root of 1311561 is about 1145.2340372168. The cubic root of 1311561 is about 109.4618619920.

Adding to 1311561 its reverse (1651131), we get a palindrome (2962692).

The spelling of 1311561 in words is "one million, three hundred eleven thousand, five hundred sixty-one".