646404 has 48 divisors (see below), whose sum is σ = 1693440. Its totient is φ = 190240.

The previous prime is 646403. The next prime is 646411. The reversal of 646404 is 404646.

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 646404.

It is not an unprimeable number, because it can be changed into a prime (646403) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7747 + ... + 7829.

It is an arithmetic number, because the mean of its divisors is an integer number (35280).

2⁶⁴⁶⁴⁰⁴ 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 646404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (846720).

646404 is an abundant number, since it is smaller than the sum of its proper divisors (1047036).

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

646404 is a wasteful number, since it uses less digits than its factorization.

646404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160 (or 158 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

The square root of 646404 is about 803.9925372788. The cubic root of 646404 is about 86.4638716666.

The spelling of 646404 in words is "six hundred forty-six thousand, four hundred four".