640542171733 has 2 divisors, whose sum is σ = 640542171734. Its totient is φ = 640542171732.

The previous prime is 640542171721. The next prime is 640542171767. The reversal of 640542171733 is 337171245046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 364015535569 + 276526636164 = 603337^2 + 525858^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640542171733 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640542171733.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640542171833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320271085866 + 320271085867.

It is an arithmetic number, because the mean of its divisors is an integer number (320271085867).

Almost surely, 2^640542171733 is an apocalyptic number.

It is an amenable number.

640542171733 is a deficient number, since it is larger than the sum of its proper divisors (1).

640542171733 is an equidigital number, since it uses as much as digits as its factorization.

640542171733 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 423360, while the sum is 43.

The spelling of 640542171733 in words is "six hundred forty billion, five hundred forty-two million, one hundred seventy-one thousand, seven hundred thirty-three".