278161 has 4 divisors (see below), whose sum is σ = 299572. Its totient is φ = 256752.

The previous prime is 278149. The next prime is 278177. The reversal of 278161 is 161872.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 176400 + 101761 = 420^2 + 319^2 .

It is a cyclic number.

It is not a de Polignac number, because 278161 - 2¹¹ = 276113 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (278111) 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, 10686 + ... + 10711.

It is an arithmetic number, because the mean of its divisors is an integer number (74893).

2²⁷⁸¹⁶¹ is an apocalyptic number.

278161 is the 305-th hex number.

It is an amenable number.

278161 is a deficient number, since it is larger than the sum of its proper divisors (21411).

278161 is a wasteful number, since it uses less digits than its factorization.

278161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21410.

The product of its digits is 672, while the sum is 25.

The square root of 278161 is about 527.4097079122. The cubic root of 278161 is about 65.2777855172.

The spelling of 278161 in words is "two hundred seventy-eight thousand, one hundred sixty-one".