28003421 has 2 divisors, whose sum is σ = 28003422. Its totient is φ = 28003420.

The previous prime is 28003343. The next prime is 28003429. The reversal of 28003421 is 12430082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27984100 + 19321 = 5290^2 + 139^2 .

It is a cyclic number.

It is not a de Polignac number, because 28003421 - 2¹⁸ = 27741277 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 28003393 and 28003402.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28003429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14001710 + 14001711.

It is an arithmetic number, because the mean of its divisors is an integer number (14001711).

Almost surely, 2^28003421 is an apocalyptic number.

It is an amenable number.

28003421 is a deficient number, since it is larger than the sum of its proper divisors (1).

28003421 is an equidigital number, since it uses as much as digits as its factorization.

28003421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 28003421 is about 5291.8258663716. The cubic root of 28003421 is about 303.6712635540.

The spelling of 28003421 in words is "twenty-eight million, three thousand, four hundred twenty-one".