28403021 has 2 divisors, whose sum is σ = 28403022. Its totient is φ = 28403020.

The previous prime is 28402987. The next prime is 28403029. The reversal of 28403021 is 12030482.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21058921 + 7344100 = 4589^2 + 2710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28403021 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 28402984 and 28403002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28403029) 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 as a sum of consecutive naturals, namely, 14201510 + 14201511.

It is an arithmetic number, because the mean of its divisors is an integer number (14201511).

Almost surely, 2^28403021 is an apocalyptic number.

It is an amenable number.

28403021 is a deficient number, since it is larger than the sum of its proper divisors (1).

28403021 is an equidigital number, since it uses as much as digits as its factorization.

28403021 is an odious number, because the sum of its binary digits is odd.

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

The square root of 28403021 is about 5329.4484705268. The cubic root of 28403021 is about 305.1088780862.

The spelling of 28403021 in words is "twenty-eight million, four hundred three thousand, twenty-one".