640554 has 8 divisors (see below), whose sum is σ = 1281120. Its totient is φ = 213516.

The previous prime is 640531. The next prime is 640579. The reversal of 640554 is 455046.

It is a sphenic number, since it is the product of 3 distinct primes.

640554 is an admirable number.

It is an unprimeable number.

640554 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, 53374 + ... + 53385.

It is an arithmetic number, because the mean of its divisors is an integer number (160140).

2⁶⁴⁰⁵⁵⁴ is an apocalyptic number.

640554 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

640554 is a wasteful number, since it uses less digits than its factorization.

640554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106764.

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 640554 is about 800.3461751017. The cubic root of 640554 is about 86.2022461970.

The spelling of 640554 in words is "six hundred forty thousand, five hundred fifty-four".