1663993 has 4 divisors (see below), whose sum is σ = 1666660. Its totient is φ = 1661328.

The previous prime is 1663973. The next prime is 1663997. The reversal of 1663993 is 3993661.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1183744 + 480249 = 1088^2 + 693^2 .

It is a cyclic number.

It is not a de Polignac number, because 1663993 - 2⁹ = 1663481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1663997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 163 + ... + 1831.

It is an arithmetic number, because the mean of its divisors is an integer number (416665).

2^1663993 is an apocalyptic number.

It is an amenable number.

1663993 is a deficient number, since it is larger than the sum of its proper divisors (2667).

1663993 is an equidigital number, since it uses as much as digits as its factorization.

1663993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2666.

The product of its digits is 26244, while the sum is 37.

The square root of 1663993 is about 1289.9585264651. The cubic root of 1663993 is about 118.4996765704.

It can be divided in two parts, 16 and 63993, that added together give a square (64009 = 253²).

The spelling of 1663993 in words is "one million, six hundred sixty-three thousand, nine hundred ninety-three".