28001621 has 2 divisors, whose sum is σ = 28001622. Its totient is φ = 28001620.

The previous prime is 28001609. The next prime is 28001651. The reversal of 28001621 is 12610082.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22193521 + 5808100 = 4711^2 + 2410^2 .

It is a cyclic number.

It is not a de Polignac number, because 28001621 - 2¹⁰ = 28000597 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 28001593 and 28001602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28001651) 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, 14000810 + 14000811.

It is an arithmetic number, because the mean of its divisors is an integer number (14000811).

Almost surely, 2^28001621 is an apocalyptic number.

It is an amenable number.

28001621 is a deficient number, since it is larger than the sum of its proper divisors (1).

28001621 is an equidigital number, since it uses as much as digits as its factorization.

28001621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 28001621 is about 5291.6557900151. The cubic root of 28001621 is about 303.6647569682.

The spelling of 28001621 in words is "twenty-eight million, one thousand, six hundred twenty-one".