505409 has 2 divisors, whose sum is σ = 505410. Its totient is φ = 505408.

The previous prime is 505399. The next prime is 505411. The reversal of 505409 is 904505.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 485809 + 19600 = 697^2 + 140^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-505409 is a prime.

Together with 505411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (505429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 252704 + 252705.

It is an arithmetic number, because the mean of its divisors is an integer number (252705).

2⁵⁰⁵⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

505409 is a deficient number, since it is larger than the sum of its proper divisors (1).

505409 is an equidigital number, since it uses as much as digits as its factorization.

505409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 505409 is about 710.9212333304. The cubic root of 505409 is about 79.6552350989.

The spelling of 505409 in words is "five hundred five thousand, four hundred nine".