278969561 has 4 divisors (see below), whose sum is σ = 300428772. Its totient is φ = 257510352.

The previous prime is 278969549. The next prime is 278969567. The reversal of 278969561 is 165969872.

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 30591961 + 248377600 = 5531^2 + 15760^2 .

It is a cyclic number.

It is not a de Polignac number, because 278969561 - 2²² = 274775257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (278969567) 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 in 3 ways as a sum of consecutive naturals, for example, 10729586 + ... + 10729611.

It is an arithmetic number, because the mean of its divisors is an integer number (75107193).

Almost surely, 2^278969561 is an apocalyptic number.

It is an amenable number.

278969561 is a deficient number, since it is larger than the sum of its proper divisors (21459211).

278969561 is a wasteful number, since it uses less digits than its factorization.

278969561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21459210.

The product of its digits is 1632960, while the sum is 53.

The square root of 278969561 is about 16702.3818960051. The cubic root of 278969561 is about 653.4097435679.

The spelling of 278969561 in words is "two hundred seventy-eight million, nine hundred sixty-nine thousand, five hundred sixty-one".