640004 has 6 divisors (see below), whose sum is σ = 1120014. Its totient is φ = 320000.

The previous prime is 639997. The next prime is 640007. The reversal of 640004 is 400046.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 4 = 800^2 + 2^2 .

It is not an unprimeable number, because it can be changed into a prime (640007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79997 + ... + 80004.

It is an arithmetic number, because the mean of its divisors is an integer number (186669).

2⁶⁴⁰⁰⁰⁴ is an apocalyptic number.

It is an amenable number.

640004 is a deficient number, since it is larger than the sum of its proper divisors (480010).

640004 is a wasteful number, since it uses less digits than its factorization.

640004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160005 (or 160003 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 640004 is about 800.0024999961. The cubic root of 640004 is about 86.1775671371.

The spelling of 640004 in words is "six hundred forty thousand, four".