640854 has 12 divisors (see below), whose sum is σ = 1388556. Its totient is φ = 213612.

The previous prime is 640853. The next prime is 640859. The reversal of 640854 is 458046.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17784 + ... + 17819.

It is an arithmetic number, because the mean of its divisors is an integer number (115713).

2⁶⁴⁰⁸⁵⁴ is an apocalyptic number.

640854 is an abundant number, since it is smaller than the sum of its proper divisors (747702).

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

640854 is a wasteful number, since it uses less digits than its factorization.

640854 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35611 (or 35608 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 640854 is about 800.5335720630. The cubic root of 640854 is about 86.2157015485.

The spelling of 640854 in words is "six hundred forty thousand, eight hundred fifty-four".