1665865963 has 2 divisors, whose sum is σ = 1665865964. Its totient is φ = 1665865962.

The previous prime is 1665865961. The next prime is 1665865991. The reversal of 1665865963 is 3695685661.

It is a weak prime.

It is an emirp because it is prime and its reverse (3695685661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1665865963 - 2¹ = 1665865961 is a prime.

Together with 1665865961, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1665865961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832932981 + 832932982.

It is an arithmetic number, because the mean of its divisors is an integer number (832932982).

Almost surely, 2^1665865963 is an apocalyptic number.

1665865963 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665865963 is an equidigital number, since it uses as much as digits as its factorization.

1665865963 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6998400, while the sum is 55.

The square root of 1665865963 is about 40815.0212911864. The cubic root of 1665865963 is about 1185.4412032489.

It can be divided in two parts, 16658 and 65963, that added together give a triangular number (82621 = T₄₀₆).

The spelling of 1665865963 in words is "one billion, six hundred sixty-five million, eight hundred sixty-five thousand, nine hundred sixty-three".