278409 has 16 divisors (see below), whose sum is σ = 404352. Its totient is φ = 169728.

The previous prime is 278393. The next prime is 278413. The reversal of 278409 is 904872.

It is not a de Polignac number, because 278409 - 2⁴ = 278393 is a prime.

It is a Curzon number.

278409 is a lucky number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (278459) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2652 + ... + 2754.

It is an arithmetic number, because the mean of its divisors is an integer number (25272).

2²⁷⁸⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

278409 is a deficient number, since it is larger than the sum of its proper divisors (125943).

278409 is a wasteful number, since it uses less digits than its factorization.

278409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176.

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 278409 is about 527.6447668650. The cubic root of 278409 is about 65.2971796594.

The spelling of 278409 in words is "two hundred seventy-eight thousand, four hundred nine".