640440665446 has 8 divisors (see below), whose sum is σ = 960705258120. Its totient is φ = 320205579408.

The previous prime is 640440665443. The next prime is 640440665453. The reversal of 640440665446 is 644566044046.

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

It is a self number, because there is not a number n which added to its sum of digits gives 640440665446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640440665441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7322316 + ... + 7409263.

It is an arithmetic number, because the mean of its divisors is an integer number (120088157265).

Almost surely, 2^640440665446 is an apocalyptic number.

640440665446 is a deficient number, since it is larger than the sum of its proper divisors (320264592674).

640440665446 is a wasteful number, since it uses less digits than its factorization.

640440665446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14753318.

The product of its (nonzero) digits is 6635520, while the sum is 49.

The spelling of 640440665446 in words is "six hundred forty billion, four hundred forty million, six hundred sixty-five thousand, four hundred forty-six".