640523 has 8 divisors (see below), whose sum is σ = 714000. Its totient is φ = 570528.

The previous prime is 640499. The next prime is 640529. The reversal of 640523 is 325046.

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

It is a cyclic number.

It is not a de Polignac number, because 640523 - 2⁸ = 640267 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640495 and 640504.

It is not an unprimeable number, because it can be changed into a prime (640529) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 473 + ... + 1226.

It is an arithmetic number, because the mean of its divisors is an integer number (89250).

2⁶⁴⁰⁵²³ is an apocalyptic number.

640523 is a deficient number, since it is larger than the sum of its proper divisors (73477).

640523 is a wasteful number, since it uses less digits than its factorization.

640523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1741.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 640523 is about 800.3268082477. The cubic root of 640523 is about 86.2008555712.

Adding to 640523 its reverse (325046), we get a palindrome (965569).

The spelling of 640523 in words is "six hundred forty thousand, five hundred twenty-three".