664402 has 4 divisors (see below), whose sum is σ = 996606. Its totient is φ = 332200.

The previous prime is 664381. The next prime is 664403. The reversal of 664402 is 204466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 204466 = 2 ⋅102233.

It can be written as a sum of positive squares in only one way, i.e., 641601 + 22801 = 801^2 + 151^2 .

It is a plaindrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (664403) by changing a digit.

664402 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166099 + ... + 166102.

2⁶⁶⁴⁴⁰² is an apocalyptic number.

664402 is a deficient number, since it is larger than the sum of its proper divisors (332204).

664402 is a wasteful number, since it uses less digits than its factorization.

664402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332203.

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 664402 is about 815.1085817239. The cubic root of 664402 is about 87.2590158252.

Adding to 664402 its reverse (204466), we get a palindrome (868868).

The spelling of 664402 in words is "six hundred sixty-four thousand, four hundred two".