278386561 has 2 divisors, whose sum is σ = 278386562. Its totient is φ = 278386560.

The previous prime is 278386553. The next prime is 278386579. The reversal of 278386561 is 165683872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 214066161 + 64320400 = 14631^2 + 8020^2 .

It is a cyclic number.

It is not a de Polignac number, because 278386561 - 2³ = 278386553 is a prime.

It is not a weakly prime, because it can be changed into another prime (278386531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139193280 + 139193281.

It is an arithmetic number, because the mean of its divisors is an integer number (139193281).

Almost surely, 2^278386561 is an apocalyptic number.

It is an amenable number.

278386561 is a deficient number, since it is larger than the sum of its proper divisors (1).

278386561 is an equidigital number, since it uses as much as digits as its factorization.

278386561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 483840, while the sum is 46.

The square root of 278386561 is about 16684.9201676244. The cubic root of 278386561 is about 652.9542535456.

The spelling of 278386561 in words is "two hundred seventy-eight million, three hundred eighty-six thousand, five hundred sixty-one".