666320687 has 2 divisors, whose sum is σ = 666320688. Its totient is φ = 666320686.

The previous prime is 666320657. The next prime is 666320731. The reversal of 666320687 is 786023666.

It is an a-pointer prime, because the next prime (666320731) can be obtained adding 666320687 to its sum of digits (44).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666320687 - 2¹⁸ = 666058543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666320657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333160343 + 333160344.

It is an arithmetic number, because the mean of its divisors is an integer number (333160344).

Almost surely, 2^666320687 is an apocalyptic number.

666320687 is a deficient number, since it is larger than the sum of its proper divisors (1).

666320687 is an equidigital number, since it uses as much as digits as its factorization.

666320687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 435456, while the sum is 44.

The square root of 666320687 is about 25813.1882377981. The cubic root of 666320687 is about 873.4293180474.

The spelling of 666320687 in words is "six hundred sixty-six million, three hundred twenty thousand, six hundred eighty-seven".