278555261 has 2 divisors, whose sum is σ = 278555262. Its totient is φ = 278555260.

The previous prime is 278555239. The next prime is 278555269. The reversal of 278555261 is 162555872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 177049636 + 101505625 = 13306^2 + 10075^2 .

It is a cyclic number.

It is not a de Polignac number, because 278555261 - 2²⁶ = 211446397 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278555269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139277630 + 139277631.

It is an arithmetic number, because the mean of its divisors is an integer number (139277631).

Almost surely, 2^278555261 is an apocalyptic number.

It is an amenable number.

278555261 is a deficient number, since it is larger than the sum of its proper divisors (1).

278555261 is an equidigital number, since it uses as much as digits as its factorization.

278555261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 168000, while the sum is 41.

The square root of 278555261 is about 16689.9748651698. The cubic root of 278555261 is about 653.0861219076.

The spelling of 278555261 in words is "two hundred seventy-eight million, five hundred fifty-five thousand, two hundred sixty-one".