1605663 has 20 divisors (see below), whose sum is σ = 2459688. Its totient is φ = 1043280.

The previous prime is 1605631. The next prime is 1605677. The reversal of 1605663 is 3665061.

It is not a de Polignac number, because 1605663 - 2⁵ = 1605631 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1605563) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3253 + ... + 3713.

2^1605663 is an apocalyptic number.

1605663 is a deficient number, since it is larger than the sum of its proper divisors (854025).

1605663 is an equidigital number, since it uses as much as digits as its factorization.

1605663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516 (or 507 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 1605663 is about 1267.1475841432. The cubic root of 1605663 is about 117.0985363197.

The spelling of 1605663 in words is "one million, six hundred five thousand, six hundred sixty-three".