664992 has 36 divisors (see below), whose sum is σ = 1891890. Its totient is φ = 221568.

The previous prime is 664973. The next prime is 664997. The reversal of 664992 is 299466.

664992 is a `hidden beast` number, since 6 + 649 + 9 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 467856 + 197136 = 684^2 + 444^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (664997) by changing a digit.

664992 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 5 ways as a sum of consecutive naturals, for example, 867 + ... + 1442.

2⁶⁶⁴⁹⁹² is an apocalyptic number.

It is an amenable number.

664992 is an abundant number, since it is smaller than the sum of its proper divisors (1226898).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

664992 is a wasteful number, since it uses less digits than its factorization.

664992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2325 (or 2314 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 664992 is about 815.4704163855. The cubic root of 664992 is about 87.2848373347.

The spelling of 664992 in words is "six hundred sixty-four thousand, nine hundred ninety-two".