640816235 has 4 divisors (see below), whose sum is σ = 768979488. Its totient is φ = 512652984.

The previous prime is 640816217. The next prime is 640816243. The reversal of 640816235 is 532618046.

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 640816235 - 2⁸ = 640815979 is a prime.

It is a super-3 number, since 3×640816235³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640816195 and 640816204.

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, 64081619 + ... + 64081628.

It is an arithmetic number, because the mean of its divisors is an integer number (192244872).

Almost surely, 2^640816235 is an apocalyptic number.

640816235 is a deficient number, since it is larger than the sum of its proper divisors (128163253).

640816235 is a wasteful number, since it uses less digits than its factorization.

640816235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128163252.

The product of its (nonzero) digits is 34560, while the sum is 35.

The square root of 640816235 is about 25314.3484016476. The cubic root of 640816235 is about 862.1400797503.

The spelling of 640816235 in words is "six hundred forty million, eight hundred sixteen thousand, two hundred thirty-five".