640856833 has 8 divisors (see below), whose sum is σ = 681137600. Its totient is φ = 601231248.

The previous prime is 640856807. The next prime is 640856857. The reversal of 640856833 is 338658046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640856833 - 2²⁵ = 607302401 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640856833.

It is not an unprimeable number, because it can be changed into a prime (640856873) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161778 + ... + 165691.

It is an arithmetic number, because the mean of its divisors is an integer number (85142200).

Almost surely, 2^640856833 is an apocalyptic number.

It is an amenable number.

640856833 is a deficient number, since it is larger than the sum of its proper divisors (40280767).

640856833 is a wasteful number, since it uses less digits than its factorization.

640856833 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327591.

The product of its (nonzero) digits is 414720, while the sum is 43.

The square root of 640856833 is about 25315.1502661944. The cubic root of 640856833 is about 862.1582859181.

The spelling of 640856833 in words is "six hundred forty million, eight hundred fifty-six thousand, eight hundred thirty-three".