1681663 has 4 divisors (see below), whose sum is σ = 1702008. Its totient is φ = 1661320.

The previous prime is 1681661. The next prime is 1681679. The reversal of 1681663 is 3661861.

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 1681663 - 2¹ = 1681661 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 (1681661) 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, 10048 + ... + 10213.

It is an arithmetic number, because the mean of its divisors is an integer number (425502).

2^1681663 is an apocalyptic number.

1681663 is a deficient number, since it is larger than the sum of its proper divisors (20345).

1681663 is an equidigital number, since it uses as much as digits as its factorization.

1681663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20344.

The product of its digits is 5184, while the sum is 31.

The square root of 1681663 is about 1296.7894971814. The cubic root of 1681663 is about 118.9176512871.

The spelling of 1681663 in words is "one million, six hundred eighty-one thousand, six hundred sixty-three".