12891621 has 4 divisors (see below), whose sum is σ = 17188832. Its totient is φ = 8594412.

The previous prime is 12891607. The next prime is 12891623. The reversal of 12891621 is 12619821.

It is a happy number.

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 not a de Polignac number, because 12891621 - 2⁷ = 12891493 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12891623) 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, 2148601 + ... + 2148606.

It is an arithmetic number, because the mean of its divisors is an integer number (4297208).

Almost surely, 2^12891621 is an apocalyptic number.

It is an amenable number.

12891621 is a deficient number, since it is larger than the sum of its proper divisors (4297211).

12891621 is an equidigital number, since it uses as much as digits as its factorization.

12891621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4297210.

The product of its digits is 1728, while the sum is 30.

The square root of 12891621 is about 3590.4903564834. The cubic root of 12891621 is about 234.4782206319.

The spelling of 12891621 in words is "twelve million, eight hundred ninety-one thousand, six hundred twenty-one".