663951 has 4 divisors (see below), whose sum is σ = 885272. Its totient is φ = 442632.

The previous prime is 663937. The next prime is 663959. The reversal of 663951 is 159366.

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 663951 - 2⁷ = 663823 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 663951.

It is not an unprimeable number, because it can be changed into a prime (663959) 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, 110656 + ... + 110661.

It is an arithmetic number, because the mean of its divisors is an integer number (221318).

2⁶⁶³⁹⁵¹ is an apocalyptic number.

663951 is a deficient number, since it is larger than the sum of its proper divisors (221321).

663951 is a wasteful number, since it uses less digits than its factorization.

663951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221320.

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

The square root of 663951 is about 814.8318845013. The cubic root of 663951 is about 87.2392673777.

The spelling of 663951 in words is "six hundred sixty-three thousand, nine hundred fifty-one".