665679643 has 2 divisors, whose sum is σ = 665679644. Its totient is φ = 665679642.

The previous prime is 665679631. The next prime is 665679653. The reversal of 665679643 is 346976566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 665679643 - 2¹⁷ = 665548571 is a prime.

It is not a weakly prime, because it can be changed into another prime (665679653) 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, 332839821 + 332839822.

It is an arithmetic number, because the mean of its divisors is an integer number (332839822).

Almost surely, 2^665679643 is an apocalyptic number.

665679643 is a deficient number, since it is larger than the sum of its proper divisors (1).

665679643 is an equidigital number, since it uses as much as digits as its factorization.

665679643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4898880, while the sum is 52.

The square root of 665679643 is about 25800.7682637552. The cubic root of 665679643 is about 873.1491295005.

The spelling of 665679643 in words is "six hundred sixty-five million, six hundred seventy-nine thousand, six hundred forty-three".