640701986 has 8 divisors (see below), whose sum is σ = 992054784. Its totient is φ = 310017060.

The previous prime is 640701931. The next prime is 640701989. The reversal of 640701986 is 689107046.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (640701989) by changing a digit.

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, 5166890 + ... + 5167013.

It is an arithmetic number, because the mean of its divisors is an integer number (124006848).

Almost surely, 2^640701986 is an apocalyptic number.

640701986 is a deficient number, since it is larger than the sum of its proper divisors (351352798).

640701986 is a wasteful number, since it uses less digits than its factorization.

640701986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10333936.

The product of its (nonzero) digits is 72576, while the sum is 41.

The square root of 640701986 is about 25312.0916954723. The cubic root of 640701986 is about 862.0888406738.

The spelling of 640701986 in words is "six hundred forty million, seven hundred one thousand, nine hundred eighty-six".