664531 has 4 divisors (see below), whose sum is σ = 759472. Its totient is φ = 569592.

The previous prime is 664529. The next prime is 664537. The reversal of 664531 is 135466.

664531 = T₂₄₁ + T₂₄₂ + ... + T₂₆₁.

664531 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 135466 = 2 ⋅67733.

It is a cyclic number.

It is not a de Polignac number, because 664531 - 2¹ = 664529 is a prime.

It is a super-2 number, since 2×664531² = 883202899922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 664496 and 664505.

It is not an unprimeable number, because it can be changed into a prime (664537) 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, 47460 + ... + 47473.

It is an arithmetic number, because the mean of its divisors is an integer number (189868).

2⁶⁶⁴⁵³¹ is an apocalyptic number.

664531 is a deficient number, since it is larger than the sum of its proper divisors (94941).

664531 is an equidigital number, since it uses as much as digits as its factorization.

664531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94940.

The product of its digits is 2160, while the sum is 25.

The square root of 664531 is about 815.1877084451. The cubic root of 664531 is about 87.2646628504.

Adding to 664531 its reverse (135466), we get a palindrome (799997).

The spelling of 664531 in words is "six hundred sixty-four thousand, five hundred thirty-one".