665951 has 8 divisors (see below), whose sum is σ = 782544. Its totient is φ = 558720.

The previous prime is 665947. The next prime is 665953. The reversal of 665951 is 159566.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 665951 - 2² = 665947 is a prime.

It is a Duffinian number.

It is a plaindrome in base 9 and base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2186 + ... + 2471.

It is an arithmetic number, because the mean of its divisors is an integer number (97818).

2⁶⁶⁵⁹⁵¹ is an apocalyptic number.

665951 is a deficient number, since it is larger than the sum of its proper divisors (116593).

665951 is a wasteful number, since it uses less digits than its factorization.

665951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4681.

The product of its digits is 8100, while the sum is 32.

The square root of 665951 is about 816.0582087082. The cubic root of 665951 is about 87.3267756603.

The spelling of 665951 in words is "six hundred sixty-five thousand, nine hundred fifty-one".