278638397 has 2 divisors, whose sum is σ = 278638398. Its totient is φ = 278638396.

The previous prime is 278638357. The next prime is 278638403. The reversal of 278638397 is 793836872.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 241926916 + 36711481 = 15554^2 + 6059^2 .

It is a cyclic number.

It is not a de Polignac number, because 278638397 - 2⁶ = 278638333 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278638357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139319198 + 139319199.

It is an arithmetic number, because the mean of its divisors is an integer number (139319199).

Almost surely, 2^278638397 is an apocalyptic number.

It is an amenable number.

278638397 is a deficient number, since it is larger than the sum of its proper divisors (1).

278638397 is an equidigital number, since it uses as much as digits as its factorization.

278638397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3048192, while the sum is 53.

The square root of 278638397 is about 16692.4652762856. The cubic root of 278638397 is about 653.1510875533.

The spelling of 278638397 in words is "two hundred seventy-eight million, six hundred thirty-eight thousand, three hundred ninety-seven".