278783993 has 2 divisors, whose sum is σ = 278783994. Its totient is φ = 278783992.

The previous prime is 278783987. The next prime is 278784001. The reversal of 278783993 is 399387872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 185313769 + 93470224 = 13613^2 + 9668^2 .

It is a cyclic number.

It is not a de Polignac number, because 278783993 - 2⁸ = 278783737 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (278783693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139391996 + 139391997.

It is an arithmetic number, because the mean of its divisors is an integer number (139391997).

Almost surely, 2^278783993 is an apocalyptic number.

It is an amenable number.

278783993 is a deficient number, since it is larger than the sum of its proper divisors (1).

278783993 is an equidigital number, since it uses as much as digits as its factorization.

278783993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4572288, while the sum is 56.

The square root of 278783993 is about 16696.8258360684. The cubic root of 278783993 is about 653.2648307035.

The spelling of 278783993 in words is "two hundred seventy-eight million, seven hundred eighty-three thousand, nine hundred ninety-three".