640111 has 4 divisors (see below), whose sum is σ = 644112. Its totient is φ = 636112.

The previous prime is 640109. The next prime is 640121. The reversal of 640111 is 111046.

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

It is a cyclic number.

It is not a de Polignac number, because 640111 - 2¹ = 640109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640091 and 640100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640121) 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, 1750 + ... + 2083.

It is an arithmetic number, because the mean of its divisors is an integer number (161028).

2⁶⁴⁰¹¹¹ is an apocalyptic number.

640111 is a deficient number, since it is larger than the sum of its proper divisors (4001).

640111 is a wasteful number, since it uses less digits than its factorization.

640111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4000.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 640111 is about 800.0693719922. The cubic root of 640111 is about 86.1823694435.

Adding to 640111 its reverse (111046), we get a palindrome (751157).

The spelling of 640111 in words is "six hundred forty thousand, one hundred eleven".