278643641 has 2 divisors, whose sum is σ = 278643642. Its totient is φ = 278643640.

The previous prime is 278643611. The next prime is 278643653. The reversal of 278643641 is 146346872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 189888400 + 88755241 = 13780^2 + 9421^2 .

It is a cyclic number.

It is not a de Polignac number, because 278643641 - 2⁶ = 278643577 is a prime.

It is not a weakly prime, because it can be changed into another prime (278643601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139321820 + 139321821.

It is an arithmetic number, because the mean of its divisors is an integer number (139321821).

Almost surely, 2^278643641 is an apocalyptic number.

It is an amenable number.

278643641 is a deficient number, since it is larger than the sum of its proper divisors (1).

278643641 is an equidigital number, since it uses as much as digits as its factorization.

278643641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 41.

The square root of 278643641 is about 16692.6223524047. The cubic root of 278643641 is about 653.1551849819.

The spelling of 278643641 in words is "two hundred seventy-eight million, six hundred forty-three thousand, six hundred forty-one".