640144 has 10 divisors (see below), whose sum is σ = 1240310. Its totient is φ = 320064.

The previous prime is 640139. The next prime is 640151. The reversal of 640144 is 441046.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 144 = 800^2 + 12^2 .

It is an Ulam number.

640144 is a modest number, since divided by 144 gives 64 as remainder.

It is an unprimeable 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 as a sum of consecutive naturals, namely, 19989 + ... + 20020.

It is an arithmetic number, because the mean of its divisors is an integer number (124031).

2⁶⁴⁰¹⁴⁴ is an apocalyptic number.

It is an amenable number.

640144 is a deficient number, since it is larger than the sum of its proper divisors (600166).

640144 is a wasteful number, since it uses less digits than its factorization.

640144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40017 (or 40011 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 640144 is about 800.0899949381. The cubic root of 640144 is about 86.1838504207.

It can be divided in two parts, 640 and 144, that added together give a square (784 = 28²).

The spelling of 640144 in words is "six hundred forty thousand, one hundred forty-four".