12491237809 has 4 divisors (see below), whose sum is σ = 12496006260. Its totient is φ = 12486469360.

The previous prime is 12491237791. The next prime is 12491237821. The reversal of 12491237809 is 90873219421.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90873219421 = 3919 ⋅23187859.

It can be written as a sum of positive squares in 2 ways, for example, as 6095237184 + 6396000625 = 78072^2 + 79975^2 .

It is a cyclic number.

It is not a de Polignac number, because 12491237809 - 2²³ = 12482849201 is a prime.

It is a super-2 number, since 2×12491237809² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12491237909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2380294 + ... + 2385535.

It is an arithmetic number, because the mean of its divisors is an integer number (3124001565).

Almost surely, 2^12491237809 is an apocalyptic number.

It is an amenable number.

12491237809 is a deficient number, since it is larger than the sum of its proper divisors (4768451).

12491237809 is an equidigital number, since it uses as much as digits as its factorization.

12491237809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4768450.

The product of its (nonzero) digits is 217728, while the sum is 46.

The spelling of 12491237809 in words is "twelve billion, four hundred ninety-one million, two hundred thirty-seven thousand, eight hundred nine".