28031321 has 2 divisors, whose sum is σ = 28031322. Its totient is φ = 28031320.

The previous prime is 28031309. The next prime is 28031369. The reversal of 28031321 is 12313082.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24364096 + 3667225 = 4936^2 + 1915^2 .

It is a cyclic number.

It is not a de Polignac number, because 28031321 - 2⁶ = 28031257 is a prime.

It is equal to p_1743302 and since 28031321 and 1743302 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 28031293 and 28031302.

It is not a weakly prime, because it can be changed into another prime (28031021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14015660 + 14015661.

It is an arithmetic number, because the mean of its divisors is an integer number (14015661).

Almost surely, 2^28031321 is an apocalyptic number.

It is an amenable number.

28031321 is a deficient number, since it is larger than the sum of its proper divisors (1).

28031321 is an equidigital number, since it uses as much as digits as its factorization.

28031321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 28031321 is about 5294.4613512613. The cubic root of 28031321 is about 303.7720799995.

The spelling of 28031321 in words is "twenty-eight million, thirty-one thousand, three hundred twenty-one".