278261 has 2 divisors, whose sum is σ = 278262. Its totient is φ = 278260.

The previous prime is 278237. The next prime is 278269. The reversal of 278261 is 162872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 244036 + 34225 = 494^2 + 185^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-278261 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 278261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139130 + 139131.

It is an arithmetic number, because the mean of its divisors is an integer number (139131).

2²⁷⁸²⁶¹ is an apocalyptic number.

It is an amenable number.

278261 is a deficient number, since it is larger than the sum of its proper divisors (1).

278261 is an equidigital number, since it uses as much as digits as its factorization.

278261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1344, while the sum is 26.

The square root of 278261 is about 527.5045023505. The cubic root of 278261 is about 65.2856071222.

The spelling of 278261 in words is "two hundred seventy-eight thousand, two hundred sixty-one".