668400670081 has 2 divisors, whose sum is σ = 668400670082. Its totient is φ = 668400670080.

The previous prime is 668400670033. The next prime is 668400670111. The reversal of 668400670081 is 180076004866.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 451840740481 + 216559929600 = 672191^2 + 465360^2 .

It is a cyclic number.

It is not a de Polignac number, because 668400670081 - 2⁹ = 668400669569 is a prime.

It is a super-2 number, since 2×668400670081² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (668400610081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334200335040 + 334200335041.

It is an arithmetic number, because the mean of its divisors is an integer number (334200335041).

Almost surely, 2^668400670081 is an apocalyptic number.

It is an amenable number.

668400670081 is a deficient number, since it is larger than the sum of its proper divisors (1).

668400670081 is an equidigital number, since it uses as much as digits as its factorization.

668400670081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 387072, while the sum is 46.

The spelling of 668400670081 in words is "six hundred sixty-eight billion, four hundred million, six hundred seventy thousand, eighty-one".