640884559 has 4 divisors (see below), whose sum is σ = 732439504. Its totient is φ = 549329616.

The previous prime is 640884551. The next prime is 640884589. The reversal of 640884559 is 955488046.

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 640884559 - 2³ = 640884551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640884551) 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, 45777462 + ... + 45777475.

It is an arithmetic number, because the mean of its divisors is an integer number (183109876).

Almost surely, 2^640884559 is an apocalyptic number.

640884559 is a deficient number, since it is larger than the sum of its proper divisors (91554945).

640884559 is an equidigital number, since it uses as much as digits as its factorization.

640884559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91554944.

The product of its (nonzero) digits is 1382400, while the sum is 49.

The square root of 640884559 is about 25315.6978770090. The cubic root of 640884559 is about 862.1707191974.

The spelling of 640884559 in words is "six hundred forty million, eight hundred eighty-four thousand, five hundred fifty-nine".