640198838 has 8 divisors (see below), whose sum is σ = 993412080. Its totient is φ = 309061480.

The previous prime is 640198817. The next prime is 640198849. The reversal of 640198838 is 838891046.

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

It is a junction number, because it is equal to n+sod(n) for n = 640198792 and 640198801.

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, 5518898 + ... + 5519013.

It is an arithmetic number, because the mean of its divisors is an integer number (124176510).

Almost surely, 2^640198838 is an apocalyptic number.

640198838 is a deficient number, since it is larger than the sum of its proper divisors (353213242).

640198838 is a wasteful number, since it uses less digits than its factorization.

640198838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11037942.

The product of its (nonzero) digits is 331776, while the sum is 47.

The square root of 640198838 is about 25302.1508571900. The cubic root of 640198838 is about 861.8631133312.

The spelling of 640198838 in words is "six hundred forty million, one hundred ninety-eight thousand, eight hundred thirty-eight".