640006398 has 12 divisors (see below), whose sum is σ = 1386680568. Its totient is φ = 213335460.

The previous prime is 640006369. The next prime is 640006417. The reversal of 640006398 is 893600046.

640006398 is a `hidden beast` number, since 640 + 0 + 0 + 6 + 3 + 9 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 17777938 + ... + 17777973.

It is an arithmetic number, because the mean of its divisors is an integer number (115556714).

Almost surely, 2^640006398 is an apocalyptic number.

640006398 is an abundant number, since it is smaller than the sum of its proper divisors (746674170).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640006398 is a wasteful number, since it uses less digits than its factorization.

640006398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35555919 (or 35555916 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 640006398 is about 25298.3477326089. The cubic root of 640006398 is about 861.7767476851.

The spelling of 640006398 in words is "six hundred forty million, six thousand, three hundred ninety-eight".