640501 has 4 divisors (see below), whose sum is σ = 642400. Its totient is φ = 638604.

The previous prime is 640499. The next prime is 640529. The reversal of 640501 is 105046.

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 640501 - 2¹ = 640499 is a prime.

It is a Duffinian number.

640501 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 291 + ... + 1168.

It is an arithmetic number, because the mean of its divisors is an integer number (160600).

2⁶⁴⁰⁵⁰¹ is an apocalyptic number.

It is an amenable number.

640501 is a deficient number, since it is larger than the sum of its proper divisors (1899).

640501 is a wasteful number, since it uses less digits than its factorization.

640501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1898.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 640501 is about 800.3130637444. The cubic root of 640501 is about 86.1998686482.

Adding to 640501 its reverse (105046), we get a palindrome (745547).

The spelling of 640501 in words is "six hundred forty thousand, five hundred one".