668844551 has 2 divisors, whose sum is σ = 668844552. Its totient is φ = 668844550.

The previous prime is 668844541. The next prime is 668844557. The reversal of 668844551 is 155448866.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668844551 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 668844496 and 668844505.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668844557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334422275 + 334422276.

It is an arithmetic number, because the mean of its divisors is an integer number (334422276).

Almost surely, 2^668844551 is an apocalyptic number.

668844551 is a deficient number, since it is larger than the sum of its proper divisors (1).

668844551 is an equidigital number, since it uses as much as digits as its factorization.

668844551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 921600, while the sum is 47.

The square root of 668844551 is about 25862.0291353946. The cubic root of 668844551 is about 874.5307093289.

The spelling of 668844551 in words is "six hundred sixty-eight million, eight hundred forty-four thousand, five hundred fifty-one".