28908409 has 2 divisors, whose sum is σ = 28908410. Its totient is φ = 28908408.

The previous prime is 28908343. The next prime is 28908413. The reversal of 28908409 is 90480982.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17040384 + 11868025 = 4128^2 + 3445^2 .

It is a cyclic number.

It is not a de Polignac number, because 28908409 - 2⁷ = 28908281 is a prime.

It is a super-2 number, since 2×28908409² = 1671392221822562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (28908469) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14454204 + 14454205.

It is an arithmetic number, because the mean of its divisors is an integer number (14454205).

Almost surely, 2^28908409 is an apocalyptic number.

It is an amenable number.

28908409 is a deficient number, since it is larger than the sum of its proper divisors (1).

28908409 is an equidigital number, since it uses as much as digits as its factorization.

28908409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 28908409 is about 5376.6540710743. The cubic root of 28908409 is about 306.9078971236.

The spelling of 28908409 in words is "twenty-eight million, nine hundred eight thousand, four hundred nine".