640145891 has 16 divisors (see below), whose sum is σ = 840111360. Its totient is φ = 472560480.

The previous prime is 640145881. The next prime is 640145893. The reversal of 640145891 is 198541046.

It is a de Polignac number, because none of the positive numbers 2^k-640145891 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640145893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 217316 + ... + 220241.

It is an arithmetic number, because the mean of its divisors is an integer number (52506960).

Almost surely, 2^640145891 is an apocalyptic number.

640145891 is a deficient number, since it is larger than the sum of its proper divisors (199965469).

640145891 is a wasteful number, since it uses less digits than its factorization.

640145891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 437594.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 640145891 is about 25301.1045411065. The cubic root of 640145891 is about 861.8393528360.

The spelling of 640145891 in words is "six hundred forty million, one hundred forty-five thousand, eight hundred ninety-one".