278618993 has 2 divisors, whose sum is σ = 278618994. Its totient is φ = 278618992.

The previous prime is 278618957. The next prime is 278618999. The reversal of 278618993 is 399816872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 167780209 + 110838784 = 12953^2 + 10528^2 .

It is a cyclic number.

It is not a de Polignac number, because 278618993 - 2⁸ = 278618737 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (278618999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139309496 + 139309497.

It is an arithmetic number, because the mean of its divisors is an integer number (139309497).

Almost surely, 2^278618993 is an apocalyptic number.

It is an amenable number.

278618993 is a deficient number, since it is larger than the sum of its proper divisors (1).

278618993 is an equidigital number, since it uses as much as digits as its factorization.

278618993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1306368, while the sum is 53.

The square root of 278618993 is about 16691.8840458470. The cubic root of 278618993 is about 653.1359256828.

The spelling of 278618993 in words is "two hundred seventy-eight million, six hundred eighteen thousand, nine hundred ninety-three".