664442 has 4 divisors (see below), whose sum is σ = 996666. Its totient is φ = 332220.

The previous prime is 664441. The next prime is 664459. The reversal of 664442 is 244466.

664442 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.

It can be written as a sum of positive squares in only one way, i.e., 461041 + 203401 = 679^2 + 451^2 .

It is an Ulam number.

It is a plaindrome in base 9.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (664441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166109 + ... + 166112.

2⁶⁶⁴⁴⁴² is an apocalyptic number.

664442 is a deficient number, since it is larger than the sum of its proper divisors (332224).

664442 is a wasteful number, since it uses less digits than its factorization.

664442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332223.

The product of its digits is 4608, while the sum is 26.

The square root of 664442 is about 815.1331179629. The cubic root of 664442 is about 87.2607669189.

The spelling of 664442 in words is "six hundred sixty-four thousand, four hundred forty-two".