278639 has 2 divisors, whose sum is σ = 278640. Its totient is φ = 278638.

The previous prime is 278627. The next prime is 278651. The reversal of 278639 is 936872.

It is a balanced prime because it is at equal distance from previous prime (278627) and next prime (278651).

It is a cyclic number.

It is not a de Polignac number, because 278639 - 2⁴ = 278623 is a prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 278599 and 278608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139319 + 139320.

It is an arithmetic number, because the mean of its divisors is an integer number (139320).

2²⁷⁸⁶³⁹ is an apocalyptic number.

278639 is a deficient number, since it is larger than the sum of its proper divisors (1).

278639 is an equidigital number, since it uses as much as digits as its factorization.

278639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 35.

The square root of 278639 is about 527.8626715349. The cubic root of 278639 is about 65.3151558713.

It can be divided in two parts, 27863 and 9, that added together give a palindrome (27872).

The spelling of 278639 in words is "two hundred seventy-eight thousand, six hundred thirty-nine".