1665505993 has 2 divisors, whose sum is σ = 1665505994. Its totient is φ = 1665505992.

The previous prime is 1665505967. The next prime is 1665506027. The reversal of 1665505993 is 3995055661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1216405129 + 449100864 = 34877^2 + 21192^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665505993 - 2⁹ = 1665505481 is a prime.

It is not a weakly prime, because it can be changed into another prime (1665505943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832752996 + 832752997.

It is an arithmetic number, because the mean of its divisors is an integer number (832752997).

Almost surely, 2^1665505993 is an apocalyptic number.

It is an amenable number.

1665505993 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665505993 is an equidigital number, since it uses as much as digits as its factorization.

1665505993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1093500, while the sum is 49.

The square root of 1665505993 is about 40810.6112794209. The cubic root of 1665505993 is about 1185.3558114228.

The spelling of 1665505993 in words is "one billion, six hundred sixty-five million, five hundred five thousand, nine hundred ninety-three".