643503754181 has 2 divisors, whose sum is σ = 643503754182. Its totient is φ = 643503754180.

The previous prime is 643503754171. The next prime is 643503754207. The reversal of 643503754181 is 181457305346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 610875112225 + 32628641956 = 781585^2 + 180634^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643503754181 is a prime.

It is a super-2 number, since 2×643503754181² (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 (643503754171) 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, 321751877090 + 321751877091.

It is an arithmetic number, because the mean of its divisors is an integer number (321751877091).

Almost surely, 2^643503754181 is an apocalyptic number.

It is an amenable number.

643503754181 is a deficient number, since it is larger than the sum of its proper divisors (1).

643503754181 is an equidigital number, since it uses as much as digits as its factorization.

643503754181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1209600, while the sum is 47.

The spelling of 643503754181 in words is "six hundred forty-three billion, five hundred three million, seven hundred fifty-four thousand, one hundred eighty-one".