640733 has 2 divisors, whose sum is σ = 640734. Its totient is φ = 640732.

The previous prime is 640727. The next prime is 640741. The reversal of 640733 is 337046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 582169 + 58564 = 763^2 + 242^2 .

It is a cyclic number.

It is not a de Polignac number, because 640733 - 2⁶ = 640669 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 640699 and 640708.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320366 + 320367.

It is an arithmetic number, because the mean of its divisors is an integer number (320367).

2⁶⁴⁰⁷³³ is an apocalyptic number.

It is an amenable number.

640733 is a deficient number, since it is larger than the sum of its proper divisors (1).

640733 is an equidigital number, since it uses as much as digits as its factorization.

640733 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1512, while the sum is 23.

The square root of 640733 is about 800.4579939010. The cubic root of 640733 is about 86.2102750621.

Adding to 640733 its reverse (337046), we get a palindrome (977779).

The spelling of 640733 in words is "six hundred forty thousand, seven hundred thirty-three".