640513 has 4 divisors (see below), whose sum is σ = 643540. Its totient is φ = 637488.

The previous prime is 640499. The next prime is 640529. The reversal of 640513 is 315046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 315046 = 2 ⋅157523.

It can be written as a sum of positive squares in 2 ways, for example, as 543169 + 97344 = 737^2 + 312^2 .

It is a cyclic number.

It is not a de Polignac number, because 640513 - 2¹³ = 632321 is a prime.

It is a Duffinian number.

640513 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (640583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1170 + ... + 1627.

It is an arithmetic number, because the mean of its divisors is an integer number (160885).

2⁶⁴⁰⁵¹³ is an apocalyptic number.

It is an amenable number.

640513 is a deficient number, since it is larger than the sum of its proper divisors (3027).

640513 is a wasteful number, since it uses less digits than its factorization.

640513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3026.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 640513 is about 800.3205607755. The cubic root of 640513 is about 86.2004069726.

Adding to 640513 its reverse (315046), we get a palindrome (955559).

The spelling of 640513 in words is "six hundred forty thousand, five hundred thirteen".