640564633 has 2 divisors, whose sum is σ = 640564634. Its totient is φ = 640564632.

The previous prime is 640564619. The next prime is 640564637. The reversal of 640564633 is 336465046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 619661449 + 20903184 = 24893^2 + 4572^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640564633 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 640564592 and 640564601.

It is not a weakly prime, because it can be changed into another prime (640564637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320282316 + 320282317.

It is an arithmetic number, because the mean of its divisors is an integer number (320282317).

Almost surely, 2^640564633 is an apocalyptic number.

It is an amenable number.

640564633 is a deficient number, since it is larger than the sum of its proper divisors (1).

640564633 is an equidigital number, since it uses as much as digits as its factorization.

640564633 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 155520, while the sum is 37.

The square root of 640564633 is about 25309.3783605999. The cubic root of 640564633 is about 862.0272317127.

The spelling of 640564633 in words is "six hundred forty million, five hundred sixty-four thousand, six hundred thirty-three".