28209397 has 2 divisors, whose sum is σ = 28209398. Its totient is φ = 28209396.

The previous prime is 28209359. The next prime is 28209407. The reversal of 28209397 is 79390282.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16859236 + 11350161 = 4106^2 + 3369^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28209397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28209347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14104698 + 14104699.

It is an arithmetic number, because the mean of its divisors is an integer number (14104699).

Almost surely, 2^28209397 is an apocalyptic number.

It is an amenable number.

28209397 is a deficient number, since it is larger than the sum of its proper divisors (1).

28209397 is an equidigital number, since it uses as much as digits as its factorization.

28209397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 28209397 is about 5311.2519239818. The cubic root of 28209397 is about 304.4139854099.

The spelling of 28209397 in words is "twenty-eight million, two hundred nine thousand, three hundred ninety-seven".