640542171767 has 2 divisors, whose sum is σ = 640542171768. Its totient is φ = 640542171766.

The previous prime is 640542171733. The next prime is 640542171779. The reversal of 640542171767 is 767171245046.

640542171767 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640542171767 - 2¹⁶ = 640542106231 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640542171167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320271085883 + 320271085884.

It is an arithmetic number, because the mean of its divisors is an integer number (320271085884).

Almost surely, 2^640542171767 is an apocalyptic number.

640542171767 is a deficient number, since it is larger than the sum of its proper divisors (1).

640542171767 is an equidigital number, since it uses as much as digits as its factorization.

640542171767 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1975680, while the sum is 50.

The spelling of 640542171767 in words is "six hundred forty billion, five hundred forty-two million, one hundred seventy-one thousand, seven hundred sixty-seven".