278961261 has 4 divisors (see below), whose sum is σ = 371948352. Its totient is φ = 185974172.

The previous prime is 278961247. The next prime is 278961269. The reversal of 278961261 is 162169872.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 278961261 - 2⁵ = 278961229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (278961269) 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, 46493541 + ... + 46493546.

It is an arithmetic number, because the mean of its divisors is an integer number (92987088).

Almost surely, 2^278961261 is an apocalyptic number.

It is an amenable number.

278961261 is a deficient number, since it is larger than the sum of its proper divisors (92987091).

278961261 is an equidigital number, since it uses as much as digits as its factorization.

278961261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92987090.

The product of its digits is 72576, while the sum is 42.

The square root of 278961261 is about 16702.1334266015. The cubic root of 278961261 is about 653.4032633452.

The spelling of 278961261 in words is "two hundred seventy-eight million, nine hundred sixty-one thousand, two hundred sixty-one".