12756421 has 4 divisors (see below), whose sum is σ = 13311072. Its totient is φ = 12201772.

The previous prime is 12756413. The next prime is 12756431. The reversal of 12756421 is 12465721.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12465721 = 1979 ⋅6299.

It is a cyclic number.

It is not a de Polignac number, because 12756421 - 2³ = 12756413 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 12756421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12756431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 277291 + ... + 277336.

It is an arithmetic number, because the mean of its divisors is an integer number (3327768).

Almost surely, 2^12756421 is an apocalyptic number.

It is an amenable number.

12756421 is a deficient number, since it is larger than the sum of its proper divisors (554651).

12756421 is an equidigital number, since it uses as much as digits as its factorization.

12756421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554650.

The product of its digits is 3360, while the sum is 28.

The square root of 12756421 is about 3571.6132209409. The cubic root of 12756421 is about 233.6556468595.

The spelling of 12756421 in words is "twelve million, seven hundred fifty-six thousand, four hundred twenty-one".