663591 has 4 divisors (see below), whose sum is σ = 884792. Its totient is φ = 442392.

The previous prime is 663589. The next prime is 663599. The reversal of 663591 is 195366.

It is a happy number.

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

It is not a de Polignac number, because 663591 - 2¹ = 663589 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110596 + ... + 110601.

It is an arithmetic number, because the mean of its divisors is an integer number (221198).

2⁶⁶³⁵⁹¹ is an apocalyptic number.

663591 is a deficient number, since it is larger than the sum of its proper divisors (221201).

663591 is a wasteful number, since it uses less digits than its factorization.

663591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221200.

The product of its digits is 4860, while the sum is 30.

The square root of 663591 is about 814.6109500860. The cubic root of 663591 is about 87.2234972309.

The spelling of 663591 in words is "six hundred sixty-three thousand, five hundred ninety-one".