640317473 has 2 divisors, whose sum is σ = 640317474. Its totient is φ = 640317472.

The previous prime is 640317443. The next prime is 640317487. The reversal of 640317473 is 374713046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 504990784 + 135326689 = 22472^2 + 11633^2 .

It is a cyclic number.

It is not a de Polignac number, because 640317473 - 2⁶ = 640317409 is a prime.

It is not a weakly prime, because it can be changed into another prime (640317443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320158736 + 320158737.

It is an arithmetic number, because the mean of its divisors is an integer number (320158737).

Almost surely, 2^640317473 is an apocalyptic number.

It is an amenable number.

640317473 is a deficient number, since it is larger than the sum of its proper divisors (1).

640317473 is an equidigital number, since it uses as much as digits as its factorization.

640317473 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 42336, while the sum is 35.

The square root of 640317473 is about 25304.4951145049. The cubic root of 640317473 is about 861.9163472169.

The spelling of 640317473 in words is "six hundred forty million, three hundred seventeen thousand, four hundred seventy-three".