664951 has 4 divisors (see below), whose sum is σ = 759952. Its totient is φ = 569952.

The previous prime is 664949. The next prime is 664967. The reversal of 664951 is 159466.

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 664951 - 2¹ = 664949 is a prime.

It is a Duffinian number.

664951 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664151) 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 3 ways as a sum of consecutive naturals, for example, 47490 + ... + 47503.

It is an arithmetic number, because the mean of its divisors is an integer number (189988).

2⁶⁶⁴⁹⁵¹ is an apocalyptic number.

664951 is a deficient number, since it is larger than the sum of its proper divisors (95001).

664951 is an equidigital number, since it uses as much as digits as its factorization.

664951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95000.

The product of its digits is 6480, while the sum is 31.

The square root of 664951 is about 815.4452771339. The cubic root of 664951 is about 87.2830434525.

The spelling of 664951 in words is "six hundred sixty-four thousand, nine hundred fifty-one".