278795561 has 4 divisors (see below), whose sum is σ = 304140624. Its totient is φ = 253450500.

The previous prime is 278795551. The next prime is 278795599. The reversal of 278795561 is 165597872.

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 278795561 - 2¹⁸ = 278533417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (278795501) 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, 12672515 + ... + 12672536.

It is an arithmetic number, because the mean of its divisors is an integer number (76035156).

Almost surely, 2^278795561 is an apocalyptic number.

It is an amenable number.

278795561 is a deficient number, since it is larger than the sum of its proper divisors (25345063).

278795561 is a wasteful number, since it uses less digits than its factorization.

278795561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25345062.

The product of its digits is 1058400, while the sum is 50.

The square root of 278795561 is about 16697.1722456229. The cubic root of 278795561 is about 653.2738662092.

The spelling of 278795561 in words is "two hundred seventy-eight million, seven hundred ninety-five thousand, five hundred sixty-one".