640655289 has 6 divisors (see below), whose sum is σ = 925390986. Its totient is φ = 427103520.

The previous prime is 640655287. The next prime is 640655293. The reversal of 640655289 is 982556046.

640655289 is a `hidden beast` number, since 64 + 0 + 65 + 528 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 420578064 + 220077225 = 20508^2 + 14835^2 .

It is not a de Polignac number, because 640655289 - 2¹ = 640655287 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640655287) 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 5 ways as a sum of consecutive naturals, for example, 35591952 + ... + 35591969.

It is an arithmetic number, because the mean of its divisors is an integer number (154231831).

Almost surely, 2^640655289 is an apocalyptic number.

It is an amenable number.

640655289 is a deficient number, since it is larger than the sum of its proper divisors (284735697).

640655289 is a wasteful number, since it uses less digits than its factorization.

640655289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71183927 (or 71183924 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 45.

The square root of 640655289 is about 25311.1692539084. The cubic root of 640655289 is about 862.0678959696.

The spelling of 640655289 in words is "six hundred forty million, six hundred fifty-five thousand, two hundred eighty-nine".