640442329 has 4 divisors (see below), whose sum is σ = 674149840. Its totient is φ = 606734820.

The previous prime is 640442323. The next prime is 640442333. The reversal of 640442329 is 923244046.

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 640442329 - 2²¹ = 638345177 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640442294 and 640442303.

It is not an unprimeable number, because it can be changed into a prime (640442323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16853727 + ... + 16853764.

It is an arithmetic number, because the mean of its divisors is an integer number (168537460).

Almost surely, 2^640442329 is an apocalyptic number.

It is an amenable number.

640442329 is a deficient number, since it is larger than the sum of its proper divisors (33707511).

640442329 is a wasteful number, since it uses less digits than its factorization.

640442329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33707510.

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 640442329 is about 25306.9620658032. The cubic root of 640442329 is about 861.9723654881.

The spelling of 640442329 in words is "six hundred forty million, four hundred forty-two thousand, three hundred twenty-nine".