28109321 has 2 divisors, whose sum is σ = 28109322. Its totient is φ = 28109320.

The previous prime is 28109317. The next prime is 28109327. The reversal of 28109321 is 12390182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28090000 + 19321 = 5300^2 + 139^2 .

It is a cyclic number.

It is not a de Polignac number, because 28109321 - 2² = 28109317 is a prime.

It is not a weakly prime, because it can be changed into another prime (28109327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14054660 + 14054661.

It is an arithmetic number, because the mean of its divisors is an integer number (14054661).

Almost surely, 2^28109321 is an apocalyptic number.

It is an amenable number.

28109321 is a deficient number, since it is larger than the sum of its proper divisors (1).

28109321 is an equidigital number, since it uses as much as digits as its factorization.

28109321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 28109321 is about 5301.8224225261. The cubic root of 28109321 is about 304.0535779586.

The spelling of 28109321 in words is "twenty-eight million, one hundred nine thousand, three hundred twenty-one".