640533723 has 4 divisors (see below), whose sum is σ = 854044968. Its totient is φ = 427022480.

The previous prime is 640533713. The next prime is 640533727. The reversal of 640533723 is 327335046.

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 640533723 - 2⁹ = 640533211 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640533727) 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, 106755618 + ... + 106755623.

It is an arithmetic number, because the mean of its divisors is an integer number (213511242).

Almost surely, 2^640533723 is an apocalyptic number.

640533723 is a deficient number, since it is larger than the sum of its proper divisors (213511245).

640533723 is a wasteful number, since it uses less digits than its factorization.

640533723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213511244.

The product of its (nonzero) digits is 45360, while the sum is 33.

The square root of 640533723 is about 25308.7677100249. The cubic root of 640533723 is about 862.0133659819.

Adding to 640533723 its reverse (327335046), we get a palindrome (967868769).

It can be divided in two parts, 64053 and 3723, that added together give a palindrome (67776).

The spelling of 640533723 in words is "six hundred forty million, five hundred thirty-three thousand, seven hundred twenty-three".