421664 has 12 divisors (see below), whose sum is σ = 830214. Its totient is φ = 210816.

The previous prime is 421661. The next prime is 421691. The reversal of 421664 is 466124.

It is a happy number.

421664 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 336400 + 85264 = 580^2 + 292^2 .

It is not an unprimeable number, because it can be changed into a prime (421661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6557 + ... + 6620.

2⁴²¹⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

421664 is a deficient number, since it is larger than the sum of its proper divisors (408550).

421664 is a wasteful number, since it uses less digits than its factorization.

421664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13187 (or 13179 counting only the distinct ones).

The product of its digits is 1152, while the sum is 23.

The square root of 421664 is about 649.3566046480. The cubic root of 421664 is about 74.9874942111.

Adding to 421664 its reverse (466124), we get a palindrome (887788).

The spelling of 421664 in words is "four hundred twenty-one thousand, six hundred sixty-four".