278681 has 12 divisors (see below), whose sum is σ = 322812. Its totient is φ = 239616.

The previous prime is 278671. The next prime is 278687. The reversal of 278681 is 186872.

278681 = T₇₈ + T₇₉ + ... + T₁₂₈.

It can be written as a sum of positive squares in 6 ways, for example, as 19600 + 259081 = 140^2 + 509^2 .

It is not a de Polignac number, because 278681 - 2⁶ = 278617 is a prime.

It is a super-2 number, since 2×278681² = 155326199522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a plaindrome in base 15.

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 278681.

It is not an unprimeable number, because it can be changed into a prime (278687) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2825 + ... + 2921.

It is an arithmetic number, because the mean of its divisors is an integer number (26901).

2²⁷⁸⁶⁸¹ is an apocalyptic number.

It is an amenable number.

278681 is a deficient number, since it is larger than the sum of its proper divisors (44131).

278681 is a wasteful number, since it uses less digits than its factorization.

278681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140 (or 127 counting only the distinct ones).

The product of its digits is 5376, while the sum is 32.

The square root of 278681 is about 527.9024531104. The cubic root of 278681 is about 65.3184374157.

Subtracting from 278681 its reverse (186872), we obtain a square (91809 = 303²).

It can be divided in two parts, 278 and 681, that added together give a palindrome (959).

The spelling of 278681 in words is "two hundred seventy-eight thousand, six hundred eighty-one".