664445531 has 4 divisors (see below), whose sum is σ = 664500432. Its totient is φ = 664390632.

The previous prime is 664445513. The next prime is 664445543. The reversal of 664445531 is 135544466.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 664445531 - 2²² = 660251227 is a prime.

It is a super-2 number, since 2×664445531² = 882975727331743922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664445581) 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, 431 + ... + 36456.

It is an arithmetic number, because the mean of its divisors is an integer number (166125108).

Almost surely, 2^664445531 is an apocalyptic number.

664445531 is a deficient number, since it is larger than the sum of its proper divisors (54901).

664445531 is a wasteful number, since it uses less digits than its factorization.

664445531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54900.

The product of its digits is 172800, while the sum is 38.

The square root of 664445531 is about 25776.8409817805. The cubic root of 664445531 is about 872.6092149336.

Adding to 664445531 its reverse (135544466), we get a palindrome (799989997).

The spelling of 664445531 in words is "six hundred sixty-four million, four hundred forty-five thousand, five hundred thirty-one".