668665566787 has 2 divisors, whose sum is σ = 668665566788. Its totient is φ = 668665566786.

The previous prime is 668665566757. The next prime is 668665566841. The reversal of 668665566787 is 787665566866.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 668665566787 - 2³⁵ = 634305828419 is a prime.

It is a super-2 number, since 2×668665566787² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (668665566757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334332783393 + 334332783394.

It is an arithmetic number, because the mean of its divisors is an integer number (334332783394).

Almost surely, 2^668665566787 is an apocalyptic number.

668665566787 is a deficient number, since it is larger than the sum of its proper divisors (1).

668665566787 is an equidigital number, since it uses as much as digits as its factorization.

668665566787 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3657830400, while the sum is 76.

The spelling of 668665566787 in words is "six hundred sixty-eight billion, six hundred sixty-five million, five hundred sixty-six thousand, seven hundred eighty-seven".