1665663 has 4 divisors (see below), whose sum is σ = 2220888. Its totient is φ = 1110440.

The previous prime is 1665659. The next prime is 1665679. The reversal of 1665663 is 3665661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1665663 - 2² = 1665659 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665623) 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, 277608 + ... + 277613.

It is an arithmetic number, because the mean of its divisors is an integer number (555222).

2^1665663 is an apocalyptic number.

1665663 is a deficient number, since it is larger than the sum of its proper divisors (555225).

1665663 is an equidigital number, since it uses as much as digits as its factorization.

1665663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555224.

The product of its digits is 19440, while the sum is 33.

The square root of 1665663 is about 1290.6056717681. The cubic root of 1665663 is about 118.5393058024.

The spelling of 1665663 in words is "one million, six hundred sixty-five thousand, six hundred sixty-three".