640665133 has 2 divisors, whose sum is σ = 640665134. Its totient is φ = 640665132.

The previous prime is 640665121. The next prime is 640665167. The reversal of 640665133 is 331566046.

It is an a-pointer prime, because the next prime (640665167) can be obtained adding 640665133 to its sum of digits (34).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 453604804 + 187060329 = 21298^2 + 13677^2 .

It is a cyclic number.

It is not a de Polignac number, because 640665133 - 2⁹ = 640664621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640665533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320332566 + 320332567.

It is an arithmetic number, because the mean of its divisors is an integer number (320332567).

Almost surely, 2^640665133 is an apocalyptic number.

It is an amenable number.

640665133 is a deficient number, since it is larger than the sum of its proper divisors (1).

640665133 is an equidigital number, since it uses as much as digits as its factorization.

640665133 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 34.

The square root of 640665133 is about 25311.3637127674. The cubic root of 640665133 is about 862.0723113201.

The spelling of 640665133 in words is "six hundred forty million, six hundred sixty-five thousand, one hundred thirty-three".