640338085 has 4 divisors (see below), whose sum is σ = 768405708. Its totient is φ = 512270464.

The previous prime is 640338073. The next prime is 640338107. The reversal of 640338085 is 580833046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 216266436 + 424071649 = 14706^2 + 20593^2 .

It is a cyclic number.

It is not a de Polignac number, because 640338085 - 2¹⁷ = 640207013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64033804 + ... + 64033813.

It is an arithmetic number, because the mean of its divisors is an integer number (192101427).

Almost surely, 2^640338085 is an apocalyptic number.

It is an amenable number.

640338085 is a deficient number, since it is larger than the sum of its proper divisors (128067623).

640338085 is a wasteful number, since it uses less digits than its factorization.

640338085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128067622.

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 640338085 is about 25304.9023906436. The cubic root of 640338085 is about 861.9255955611.

The spelling of 640338085 in words is "six hundred forty million, three hundred thirty-eight thousand, eighty-five".