28791409 has 2 divisors, whose sum is σ = 28791410. Its totient is φ = 28791408.

The previous prime is 28791407. The next prime is 28791431. The reversal of 28791409 is 90419782.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22896225 + 5895184 = 4785^2 + 2428^2 .

It is a cyclic number.

It is not a de Polignac number, because 28791409 - 2¹ = 28791407 is a prime.

Together with 28791407, it forms a pair of twin primes.

It is equal to p_1787557 and since 28791409 and 1787557 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (28791407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14395704 + 14395705.

It is an arithmetic number, because the mean of its divisors is an integer number (14395705).

Almost surely, 2^28791409 is an apocalyptic number.

It is an amenable number.

28791409 is a deficient number, since it is larger than the sum of its proper divisors (1).

28791409 is an equidigital number, since it uses as much as digits as its factorization.

28791409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 28791409 is about 5365.7626671332. The cubic root of 28791409 is about 306.4932913878.

The spelling of 28791409 in words is "twenty-eight million, seven hundred ninety-one thousand, four hundred nine".