1668721823 has 2 divisors, whose sum is σ = 1668721824. Its totient is φ = 1668721822.

The previous prime is 1668721763. The next prime is 1668721877. The reversal of 1668721823 is 3281278661.

It is a strong prime.

It is an emirp because it is prime and its reverse (3281278661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1668721823 - 2¹⁶ = 1668656287 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1668721883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834360911 + 834360912.

It is an arithmetic number, because the mean of its divisors is an integer number (834360912).

Almost surely, 2^1668721823 is an apocalyptic number.

1668721823 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668721823 is an equidigital number, since it uses as much as digits as its factorization.

1668721823 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 44.

The square root of 1668721823 is about 40849.9917135855. The cubic root of 1668721823 is about 1186.1182327788.

The spelling of 1668721823 in words is "one billion, six hundred sixty-eight million, seven hundred twenty-one thousand, eight hundred twenty-three".