278661 has 8 divisors (see below), whose sum is σ = 384480. Its totient is φ = 179312.

The previous prime is 278651. The next prime is 278671. The reversal of 278661 is 166872.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (278651) and next prime (278671).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 278661 - 2⁹ = 278149 is a prime.

It is a zygodrome in base 6.

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 278661.

It is not an unprimeable number, because it can be changed into a prime (278611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1515 + ... + 1688.

It is an arithmetic number, because the mean of its divisors is an integer number (48060).

2²⁷⁸⁶⁶¹ is an apocalyptic number.

It is an amenable number.

278661 is a deficient number, since it is larger than the sum of its proper divisors (105819).

278661 is a wasteful number, since it uses less digits than its factorization.

278661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3235.

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

The square root of 278661 is about 527.8835098769. The cubic root of 278661 is about 65.3168748167.

Subtracting from 278661 its sum of digits (30), we obtain a triangular number (278631 = T₇₄₆).

It can be divided in two parts, 278 and 661, that added together give a palindrome (939).

The spelling of 278661 in words is "two hundred seventy-eight thousand, six hundred sixty-one".