640668335 has 8 divisors (see below), whose sum is σ = 802228320. Its totient is φ = 490250464.

The previous prime is 640668331. The next prime is 640668349. The reversal of 640668335 is 533866046.

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 640668335 - 2² = 640668331 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 640668292 and 640668301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640668331) 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, 2785400 + ... + 2785629.

It is an arithmetic number, because the mean of its divisors is an integer number (100278540).

Almost surely, 2^640668335 is an apocalyptic number.

640668335 is a deficient number, since it is larger than the sum of its proper divisors (161559985).

640668335 is a wasteful number, since it uses less digits than its factorization.

640668335 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5571057.

The product of its (nonzero) digits is 311040, while the sum is 41.

The square root of 640668335 is about 25311.4269649105. The cubic root of 640668335 is about 862.0737475103.

The spelling of 640668335 in words is "six hundred forty million, six hundred sixty-eight thousand, three hundred thirty-five".