640106 has 4 divisors (see below), whose sum is σ = 960162. Its totient is φ = 320052.

The previous prime is 640099. The next prime is 640109. The reversal of 640106 is 601046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 511225 + 128881 = 715^2 + 359^2 .

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640106.

It is not an unprimeable number, because it can be changed into a prime (640109) by changing a digit.

640106 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 as a sum of consecutive naturals, namely, 160025 + ... + 160028.

2⁶⁴⁰¹⁰⁶ is an apocalyptic number.

640106 is a deficient number, since it is larger than the sum of its proper divisors (320056).

640106 is a wasteful number, since it uses less digits than its factorization.

640106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320055.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 640106 is about 800.0662472571. The cubic root of 640106 is about 86.1821450486.

Subtracting from 640106 its reverse (601046), we obtain a triangular number (39060 = T₂₇₉).

The spelling of 640106 in words is "six hundred forty thousand, one hundred six".