640728472665 has 32 divisors (see below), whose sum is σ = 1071325956096. Its totient is φ = 326673224640.

The previous prime is 640728472661. The next prime is 640728472673. The reversal of 640728472665 is 566274827046.

It is not a de Polignac number, because 640728472665 - 2² = 640728472661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640728472661) 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 31 ways as a sum of consecutive naturals, for example, 10537531 + ... + 10598160.

It is an arithmetic number, because the mean of its divisors is an integer number (33478936128).

Almost surely, 2^640728472665 is an apocalyptic number.

It is an amenable number.

640728472665 is a deficient number, since it is larger than the sum of its proper divisors (430597483431).

640728472665 is a wasteful number, since it uses less digits than its factorization.

640728472665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21135789.

The product of its (nonzero) digits is 27095040, while the sum is 57.

The spelling of 640728472665 in words is "six hundred forty billion, seven hundred twenty-eight million, four hundred seventy-two thousand, six hundred sixty-five".