12643968637 has 4 divisors (see below), whose sum is σ = 13387731516. Its totient is φ = 11900205760.

The previous prime is 12643968611. The next prime is 12643968643. The reversal of 12643968637 is 73686934621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73686934621 = 31 ⋅2376997891.

It can be written as a sum of positive squares in 2 ways, for example, as 10619508601 + 2024460036 = 103051^2 + 44994^2 .

It is a cyclic number.

It is not a de Polignac number, because 12643968637 - 2¹⁹ = 12643444349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12643968647) 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, 371881414 + ... + 371881447.

It is an arithmetic number, because the mean of its divisors is an integer number (3346932879).

Almost surely, 2^12643968637 is an apocalyptic number.

12643968637 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

12643968637 is a deficient number, since it is larger than the sum of its proper divisors (743762879).

12643968637 is an equidigital number, since it uses as much as digits as its factorization.

12643968637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743762878.

The product of its digits is 7838208, while the sum is 55.

The spelling of 12643968637 in words is "twelve billion, six hundred forty-three million, nine hundred sixty-eight thousand, six hundred thirty-seven".