398664 has 72 divisors (see below), whose sum is σ = 1267110. Its totient is φ = 112896.

The previous prime is 398627. The next prime is 398669. The reversal of 398664 is 466893.

It can be written as a sum of positive squares in only one way, i.e., 396900 + 1764 = 630^2 + 42^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398669) by changing a digit.

398664 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 3472 + ... + 3584.

2³⁹⁸⁶⁶⁴ 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 398664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (633555).

398664 is an abundant number, since it is smaller than the sum of its proper divisors (868446).

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

398664 is a wasteful number, since it uses less digits than its factorization.

398664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139 (or 125 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 398664 is about 631.3984478917. The cubic root of 398664 is about 73.5985073736.

The spelling of 398664 in words is "three hundred ninety-eight thousand, six hundred sixty-four".