1666684993 has 2 divisors, whose sum is σ = 1666684994. Its totient is φ = 1666684992.

The previous prime is 1666684979. The next prime is 1666685021. The reversal of 1666684993 is 3994866661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1472026689 + 194658304 = 38367^2 + 13952^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666684993 - 2¹⁷ = 1666553921 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666684193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833342496 + 833342497.

It is an arithmetic number, because the mean of its divisors is an integer number (833342497).

Almost surely, 2^1666684993 is an apocalyptic number.

It is an amenable number.

1666684993 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666684993 is an equidigital number, since it uses as much as digits as its factorization.

1666684993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10077696, while the sum is 58.

The square root of 1666684993 is about 40825.0534965969. The cubic root of 1666684993 is about 1185.6354471349.

The spelling of 1666684993 in words is "one billion, six hundred sixty-six million, six hundred eighty-four thousand, nine hundred ninety-three".