28447421 has 2 divisors, whose sum is σ = 28447422. Its totient is φ = 28447420.

The previous prime is 28447369. The next prime is 28447451. The reversal of 28447421 is 12474482.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20124196 + 8323225 = 4486^2 + 2885^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28447421 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28447451) 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, 14223710 + 14223711.

It is an arithmetic number, because the mean of its divisors is an integer number (14223711).

Almost surely, 2^28447421 is an apocalyptic number.

It is an amenable number.

28447421 is a deficient number, since it is larger than the sum of its proper divisors (1).

28447421 is an equidigital number, since it uses as much as digits as its factorization.

28447421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14336, while the sum is 32.

The square root of 28447421 is about 5333.6123781167. The cubic root of 28447421 is about 305.2677788060.

The spelling of 28447421 in words is "twenty-eight million, four hundred forty-seven thousand, four hundred twenty-one".