640189 has 4 divisors (see below), whose sum is σ = 698400. Its totient is φ = 581980.

The previous prime is 640163. The next prime is 640193. The reversal of 640189 is 981046.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 640189 - 2⁷ = 640061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640109) 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 3 ways as a sum of consecutive naturals, for example, 29089 + ... + 29110.

It is an arithmetic number, because the mean of its divisors is an integer number (174600).

2⁶⁴⁰¹⁸⁹ is an apocalyptic number.

It is an amenable number.

640189 is a deficient number, since it is larger than the sum of its proper divisors (58211).

640189 is a wasteful number, since it uses less digits than its factorization.

640189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58210.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 640189 is about 800.1181162803. The cubic root of 640189 is about 86.1858698530.

The spelling of 640189 in words is "six hundred forty thousand, one hundred eighty-nine".