640661093 has 2 divisors, whose sum is σ = 640661094. Its totient is φ = 640661092.

The previous prime is 640661081. The next prime is 640661129. The reversal of 640661093 is 390166046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 536478244 + 104182849 = 23162^2 + 10207^2 .

It is a cyclic number.

It is not a de Polignac number, because 640661093 - 2⁶ = 640661029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640661023) 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 as a sum of consecutive naturals, namely, 320330546 + 320330547.

It is an arithmetic number, because the mean of its divisors is an integer number (320330547).

Almost surely, 2^640661093 is an apocalyptic number.

It is an amenable number.

640661093 is a deficient number, since it is larger than the sum of its proper divisors (1).

640661093 is an equidigital number, since it uses as much as digits as its factorization.

640661093 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 640661093 is about 25311.2839065900. The cubic root of 640661093 is about 862.0704992557.

The spelling of 640661093 in words is "six hundred forty million, six hundred sixty-one thousand, ninety-three".