668540987 has 2 divisors, whose sum is σ = 668540988. Its totient is φ = 668540986.

The previous prime is 668540969. The next prime is 668541037. The reversal of 668540987 is 789045866.

668540987 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 668540987 - 2⁶ = 668540923 is a prime.

It is not a weakly prime, because it can be changed into another prime (668540687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334270493 + 334270494.

It is an arithmetic number, because the mean of its divisors is an integer number (334270494).

Almost surely, 2^668540987 is an apocalyptic number.

668540987 is a deficient number, since it is larger than the sum of its proper divisors (1).

668540987 is an equidigital number, since it uses as much as digits as its factorization.

668540987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2903040, while the sum is 53.

The square root of 668540987 is about 25856.1595562837. The cubic root of 668540987 is about 874.3983835076.

The spelling of 668540987 in words is "six hundred sixty-eight million, five hundred forty thousand, nine hundred eighty-seven".