640441 has 8 divisors (see below), whose sum is σ = 686664. Its totient is φ = 595200.

The previous prime is 640421. The next prime is 640457. The reversal of 640441 is 144046.

It can be written as a sum of positive squares in 4 ways, for example, as 364816 + 275625 = 604^2 + 525^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640441 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640411) 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 7 ways as a sum of consecutive naturals, for example, 1531 + ... + 1903.

It is an arithmetic number, because the mean of its divisors is an integer number (85833).

2⁶⁴⁰⁴⁴¹ is an apocalyptic number.

It is an amenable number.

640441 is a deficient number, since it is larger than the sum of its proper divisors (46223).

640441 is a wasteful number, since it uses less digits than its factorization.

640441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 491.

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

The square root of 640441 is about 800.2755775356. The cubic root of 640441 is about 86.1971769253.

Adding to 640441 its reverse (144046), we get a palindrome (784487).

It can be divided in two parts, 640 and 441, that added together give a triangular number (1081 = T₄₆).

The spelling of 640441 in words is "six hundred forty thousand, four hundred forty-one".