640255236665 has 32 divisors (see below), whose sum is σ = 934163591040. Its totient is φ = 415183795200.

The previous prime is 640255236617. The next prime is 640255236667. The reversal of 640255236665 is 566632552046.

It is not a de Polignac number, because 640255236665 - 2⁶ = 640255236601 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640255236667) 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, 18002366 + ... + 18037895.

It is an arithmetic number, because the mean of its divisors is an integer number (29192612220).

Almost surely, 2^640255236665 is an apocalyptic number.

It is an amenable number.

640255236665 is a deficient number, since it is larger than the sum of its proper divisors (293908354375).

640255236665 is a wasteful number, since it uses less digits than its factorization.

640255236665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36040313.

The product of its (nonzero) digits is 7776000, while the sum is 50.

The spelling of 640255236665 in words is "six hundred forty billion, two hundred fifty-five million, two hundred thirty-six thousand, six hundred sixty-five".