12918421 has 2 divisors, whose sum is σ = 12918422. Its totient is φ = 12918420.

The previous prime is 12918391. The next prime is 12918443. The reversal of 12918421 is 12481921.

12918421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7344100 + 5574321 = 2710^2 + 2361^2 .

It is a cyclic number.

It is not a de Polignac number, because 12918421 - 2⁷ = 12918293 is a prime.

It is a super-2 number, since 2×12918421² = 333771202266482, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 12918421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12918481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6459210 + 6459211.

It is an arithmetic number, because the mean of its divisors is an integer number (6459211).

Almost surely, 2^12918421 is an apocalyptic number.

It is an amenable number.

12918421 is a deficient number, since it is larger than the sum of its proper divisors (1).

12918421 is an equidigital number, since it uses as much as digits as its factorization.

12918421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 28.

The square root of 12918421 is about 3594.2204996355. The cubic root of 12918421 is about 234.6405913890.

The spelling of 12918421 in words is "twelve million, nine hundred eighteen thousand, four hundred twenty-one".