640336455221 has 2 divisors, whose sum is σ = 640336455222. Its totient is φ = 640336455220.

The previous prime is 640336455191. The next prime is 640336455257. The reversal of 640336455221 is 122554633046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 416502436900 + 223834018321 = 645370^2 + 473111^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640336455221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640336425221) 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 as a sum of consecutive naturals, namely, 320168227610 + 320168227611.

It is an arithmetic number, because the mean of its divisors is an integer number (320168227611).

Almost surely, 2^640336455221 is an apocalyptic number.

It is an amenable number.

640336455221 is a deficient number, since it is larger than the sum of its proper divisors (1).

640336455221 is an equidigital number, since it uses as much as digits as its factorization.

640336455221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 518400, while the sum is 41.

The spelling of 640336455221 in words is "six hundred forty billion, three hundred thirty-six million, four hundred fifty-five thousand, two hundred twenty-one".