12811531 has 4 divisors (see below), whose sum is σ = 13053312. Its totient is φ = 12569752.

The previous prime is 12811511. The next prime is 12811541. The reversal of 12811531 is 13511821.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 12811531 - 2⁵ = 12811499 is a prime.

It is a super-2 number, since 2×12811531² = 328270653127922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12811511) 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 in 3 ways as a sum of consecutive naturals, for example, 120811 + ... + 120916.

It is an arithmetic number, because the mean of its divisors is an integer number (3263328).

Almost surely, 2^12811531 is an apocalyptic number.

12811531 is a deficient number, since it is larger than the sum of its proper divisors (241781).

12811531 is an equidigital number, since it uses as much as digits as its factorization.

12811531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241780.

The product of its digits is 240, while the sum is 22.

The square root of 12811531 is about 3579.3199074685. The cubic root of 12811531 is about 233.9916414089.

The spelling of 12811531 in words is "twelve million, eight hundred eleven thousand, five hundred thirty-one".