665278387 has 2 divisors, whose sum is σ = 665278388. Its totient is φ = 665278386.

The previous prime is 665278343. The next prime is 665278409. The reversal of 665278387 is 783872566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 665278387 - 2¹⁵ = 665245619 is a prime.

It is not a weakly prime, because it can be changed into another prime (665273387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332639193 + 332639194.

It is an arithmetic number, because the mean of its divisors is an integer number (332639194).

Almost surely, 2^665278387 is an apocalyptic number.

665278387 is a deficient number, since it is larger than the sum of its proper divisors (1).

665278387 is an equidigital number, since it uses as much as digits as its factorization.

665278387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3386880, while the sum is 52.

The square root of 665278387 is about 25792.9910440802. The cubic root of 665278387 is about 872.9736563331.

The spelling of 665278387 in words is "six hundred sixty-five million, two hundred seventy-eight thousand, three hundred eighty-seven".