401664 has 36 divisors (see below), whose sum is σ = 1071056. Its totient is φ = 133632.

The previous prime is 401651. The next prime is 401669. The reversal of 401664 is 466104.

It is a super-2 number, since 2×401664² = 322667937792, which contains 22 as substring.

It is a nialpdrome in base 14 and base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 401664.

It is not an unprimeable number, because it can be changed into a prime (401669) by changing a digit.

401664 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 in 3 ways as a sum of consecutive naturals, for example, 507 + ... + 1029.

2⁴⁰¹⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 401664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (535528).

401664 is an abundant number, since it is smaller than the sum of its proper divisors (669392).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

401664 is an equidigital number, since it uses as much as digits as its factorization.

401664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 542 (or 528 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 401664 is about 633.7696742508. The cubic root of 401664 is about 73.7826590965.

Adding to 401664 its reverse (466104), we get a palindrome (867768).

The spelling of 401664 in words is "four hundred one thousand, six hundred sixty-four".