278389 has 4 divisors (see below), whose sum is σ = 280224. Its totient is φ = 276556.

The previous prime is 278387. The next prime is 278393. The reversal of 278389 is 983872.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 278389 - 2¹ = 278387 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

278389 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (278387) 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, 667 + ... + 1000.

It is an arithmetic number, because the mean of its divisors is an integer number (70056).

2²⁷⁸³⁸⁹ is an apocalyptic number.

278389 is the 334-th heptagonal number.

It is an amenable number.

278389 is a deficient number, since it is larger than the sum of its proper divisors (1835).

278389 is a wasteful number, since it uses less digits than its factorization.

278389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1834.

The product of its digits is 24192, while the sum is 37.

The square root of 278389 is about 527.6258143799. The cubic root of 278389 is about 65.2956160427.

The spelling of 278389 in words is "two hundred seventy-eight thousand, three hundred eighty-nine".