668644489 has 2 divisors, whose sum is σ = 668644490. Its totient is φ = 668644488.

The previous prime is 668644421. The next prime is 668644499. The reversal of 668644489 is 984446866.

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., 378964089 + 289680400 = 19467^2 + 17020^2 .

It is a cyclic number.

It is not a de Polignac number, because 668644489 - 2⁹ = 668643977 is a prime.

It is a super-2 number, since 2×668644489² = 894170905340142242, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (668644499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334322244 + 334322245.

It is an arithmetic number, because the mean of its divisors is an integer number (334322245).

Almost surely, 2^668644489 is an apocalyptic number.

It is an amenable number.

668644489 is a deficient number, since it is larger than the sum of its proper divisors (1).

668644489 is an equidigital number, since it uses as much as digits as its factorization.

668644489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7962624, while the sum is 55.

The square root of 668644489 is about 25858.1609748257. The cubic root of 668644489 is about 874.4435053042.

The spelling of 668644489 in words is "six hundred sixty-eight million, six hundred forty-four thousand, four hundred eighty-nine".