28440409 has 2 divisors, whose sum is σ = 28440410. Its totient is φ = 28440408.

The previous prime is 28440407. The next prime is 28440413. The reversal of 28440409 is 90404482.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27594009 + 846400 = 5253^2 + 920^2 .

It is a cyclic number.

It is not a de Polignac number, because 28440409 - 2¹ = 28440407 is a prime.

Together with 28440407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (28440407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14220204 + 14220205.

It is an arithmetic number, because the mean of its divisors is an integer number (14220205).

Almost surely, 2^28440409 is an apocalyptic number.

It is an amenable number.

28440409 is a deficient number, since it is larger than the sum of its proper divisors (1).

28440409 is an equidigital number, since it uses as much as digits as its factorization.

28440409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 31.

The square root of 28440409 is about 5332.9549969974. The cubic root of 28440409 is about 305.2426949438.

The spelling of 28440409 in words is "twenty-eight million, four hundred forty thousand, four hundred nine".