12781621 has 4 divisors (see below), whose sum is σ = 13078912. Its totient is φ = 12484332.

The previous prime is 12781619. The next prime is 12781631. The reversal of 12781621 is 12618721.

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.

It is a cyclic number.

It is not a de Polignac number, because 12781621 - 2¹ = 12781619 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 12781621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12781631) 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, 148581 + ... + 148666.

It is an arithmetic number, because the mean of its divisors is an integer number (3269728).

Almost surely, 2^12781621 is an apocalyptic number.

It is an amenable number.

12781621 is a deficient number, since it is larger than the sum of its proper divisors (297291).

12781621 is an equidigital number, since it uses as much as digits as its factorization.

12781621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297290.

The product of its digits is 1344, while the sum is 28.

The square root of 12781621 is about 3575.1392979855. The cubic root of 12781621 is about 233.8094060074.

The spelling of 12781621 in words is "twelve million, seven hundred eighty-one thousand, six hundred twenty-one".