663391 has 4 divisors (see below), whose sum is σ = 702432. Its totient is φ = 624352.

The previous prime is 663371. The next prime is 663407. The reversal of 663391 is 193366.

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 663391 - 2⁵ = 663359 is a prime.

It is a Duffinian number.

663391 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663301) 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, 19495 + ... + 19528.

It is an arithmetic number, because the mean of its divisors is an integer number (175608).

2⁶⁶³³⁹¹ is an apocalyptic number.

663391 is a deficient number, since it is larger than the sum of its proper divisors (39041).

663391 is a wasteful number, since it uses less digits than its factorization.

663391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39040.

The product of its digits is 2916, while the sum is 28.

The square root of 663391 is about 814.4881828486. The cubic root of 663391 is about 87.2147335736.

It can be divided in two parts, 6633 and 91, that added together give a square (6724 = 82²).

The spelling of 663391 in words is "six hundred sixty-three thousand, three hundred ninety-one".