402509 has 4 divisors (see below), whose sum is σ = 426204. Its totient is φ = 378816.

The previous prime is 402503. The next prime is 402511. The reversal of 402509 is 905204.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 240100 + 162409 = 490^2 + 403^2 .

It is a cyclic number.

It is not a de Polignac number, because 402509 - 2⁸ = 402253 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 402509.

It is not an unprimeable number, because it can be changed into a prime (402503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11822 + ... + 11855.

It is an arithmetic number, because the mean of its divisors is an integer number (106551).

2⁴⁰²⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

402509 is a deficient number, since it is larger than the sum of its proper divisors (23695).

402509 is a wasteful number, since it uses less digits than its factorization.

402509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23694.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 402509 is about 634.4359699765. The cubic root of 402509 is about 73.8343629067.

The spelling of 402509 in words is "four hundred two thousand, five hundred nine".