666651823 has 2 divisors, whose sum is σ = 666651824. Its totient is φ = 666651822.

The previous prime is 666651751. The next prime is 666651827. The reversal of 666651823 is 328156666.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666651823 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 666651823.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666651827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333325911 + 333325912.

It is an arithmetic number, because the mean of its divisors is an integer number (333325912).

Almost surely, 2^666651823 is an apocalyptic number.

666651823 is a deficient number, since it is larger than the sum of its proper divisors (1).

666651823 is an equidigital number, since it uses as much as digits as its factorization.

666651823 is an evil number, because the sum of its binary digits is even.

The product of its digits is 311040, while the sum is 43.

The square root of 666651823 is about 25819.6015267471. The cubic root of 666651823 is about 873.5739811196.

The spelling of 666651823 in words is "six hundred sixty-six million, six hundred fifty-one thousand, eight hundred twenty-three".