864509 has 2 divisors, whose sum is σ = 864510. Its totient is φ = 864508.

The previous prime is 864503. The next prime is 864511. The reversal of 864509 is 905468.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 727609 + 136900 = 853^2 + 370^2 .

It is a cyclic number.

It is not a de Polignac number, because 864509 - 2¹² = 860413 is a prime.

It is a super-2 number, since 2×864509² = 1494751622162, which contains 22 as substring.

Together with 864511, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (864503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432254 + 432255.

It is an arithmetic number, because the mean of its divisors is an integer number (432255).

2⁸⁶⁴⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

864509 is a deficient number, since it is larger than the sum of its proper divisors (1).

864509 is an equidigital number, since it uses as much as digits as its factorization.

864509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 864509 is about 929.7897611826. The cubic root of 864509 is about 95.2627628524.

The spelling of 864509 in words is "eight hundred sixty-four thousand, five hundred nine".