1665311663 has 4 divisors (see below), whose sum is σ = 1684023120. Its totient is φ = 1646600208.

The previous prime is 1665311657. The next prime is 1665311671. The reversal of 1665311663 is 3661135661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3661135661 = 71 ⋅51565291.

It is a cyclic number.

It is not a de Polignac number, because 1665311663 - 2²⁰ = 1664263087 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665316663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9355595 + ... + 9355772.

It is an arithmetic number, because the mean of its divisors is an integer number (421005780).

Almost surely, 2^1665311663 is an apocalyptic number.

1665311663 is a deficient number, since it is larger than the sum of its proper divisors (18711457).

1665311663 is an equidigital number, since it uses as much as digits as its factorization.

1665311663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18711456.

The product of its digits is 58320, while the sum is 38.

The square root of 1665311663 is about 40808.2303340882. The cubic root of 1665311663 is about 1185.3097074850.

The spelling of 1665311663 in words is "one billion, six hundred sixty-five million, three hundred eleven thousand, six hundred sixty-three".