640820611069 has 2 divisors, whose sum is σ = 640820611070. Its totient is φ = 640820611068.

The previous prime is 640820611061. The next prime is 640820611099. The reversal of 640820611069 is 960116028046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 640699390969 + 121220100 = 800437^2 + 11010^2 .

It is a cyclic number.

It is not a de Polignac number, because 640820611069 - 2³ = 640820611061 is a prime.

It is a super-2 number, since 2×640820611069² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640820611061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320410305534 + 320410305535.

It is an arithmetic number, because the mean of its divisors is an integer number (320410305535).

Almost surely, 2^640820611069 is an apocalyptic number.

It is an amenable number.

640820611069 is a deficient number, since it is larger than the sum of its proper divisors (1).

640820611069 is an equidigital number, since it uses as much as digits as its factorization.

640820611069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 124416, while the sum is 43.

The spelling of 640820611069 in words is "six hundred forty billion, eight hundred twenty million, six hundred eleven thousand, sixty-nine".