640459889 has 2 divisors, whose sum is σ = 640459890. Its totient is φ = 640459888.

The previous prime is 640459861. The next prime is 640459891. The reversal of 640459889 is 988954046.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 394221025 + 246238864 = 19855^2 + 15692^2 .

It is a cyclic number.

It is not a de Polignac number, because 640459889 - 2¹⁶ = 640394353 is a prime.

Together with 640459891, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640459889.

It is not a weakly prime, because it can be changed into another prime (640459829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320229944 + 320229945.

It is an arithmetic number, because the mean of its divisors is an integer number (320229945).

Almost surely, 2^640459889 is an apocalyptic number.

It is an amenable number.

640459889 is a deficient number, since it is larger than the sum of its proper divisors (1).

640459889 is an equidigital number, since it uses as much as digits as its factorization.

640459889 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2488320, while the sum is 53.

The square root of 640459889 is about 25307.3090035270. The cubic root of 640459889 is about 861.9802434269.

The spelling of 640459889 in words is "six hundred forty million, four hundred fifty-nine thousand, eight hundred eighty-nine".