640555061 has 2 divisors, whose sum is σ = 640555062. Its totient is φ = 640555060.

The previous prime is 640555031. The next prime is 640555067. The reversal of 640555061 is 160555046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 581726161 + 58828900 = 24119^2 + 7670^2 .

It is a cyclic number.

It is not a de Polignac number, because 640555061 - 2¹⁴ = 640538677 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640555067) 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, 320277530 + 320277531.

It is an arithmetic number, because the mean of its divisors is an integer number (320277531).

Almost surely, 2^640555061 is an apocalyptic number.

It is an amenable number.

640555061 is a deficient number, since it is larger than the sum of its proper divisors (1).

640555061 is an equidigital number, since it uses as much as digits as its factorization.

640555061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18000, while the sum is 32.

The square root of 640555061 is about 25309.1892600296. The cubic root of 640555061 is about 862.0229379146.

The spelling of 640555061 in words is "six hundred forty million, five hundred fifty-five thousand, sixty-one".