640331786 has 8 divisors (see below), whose sum is σ = 963174240. Its totient is φ = 319273708.

The previous prime is 640331777. The next prime is 640331851. The reversal of 640331786 is 687133046.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 445196 + ... + 446631.

It is an arithmetic number, because the mean of its divisors is an integer number (120396780).

Almost surely, 2^640331786 is an apocalyptic number.

640331786 is a deficient number, since it is larger than the sum of its proper divisors (322842454).

640331786 is a wasteful number, since it uses less digits than its factorization.

640331786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 892188.

The product of its (nonzero) digits is 72576, while the sum is 38.

The square root of 640331786 is about 25304.7779282886. Note that the first 3 decimals coincide. The cubic root of 640331786 is about 861.9227693004.

The spelling of 640331786 in words is "six hundred forty million, three hundred thirty-one thousand, seven hundred eighty-six".