261278 has 4 divisors (see below), whose sum is σ = 391920. Its totient is φ = 130638.

The previous prime is 261271. The next prime is 261281. The reversal of 261278 is 872162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 872162 = 2 ⋅436081.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65318 + ... + 65321.

It is an arithmetic number, because the mean of its divisors is an integer number (97980).

2²⁶¹²⁷⁸ is an apocalyptic number.

261278 is a deficient number, since it is larger than the sum of its proper divisors (130642).

261278 is a wasteful number, since it uses less digits than its factorization.

261278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130641.

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

The square root of 261278 is about 511.1535972680. The cubic root of 261278 is about 63.9294469912.

The spelling of 261278 in words is "two hundred sixty-one thousand, two hundred seventy-eight".