645813617 has 2 divisors, whose sum is σ = 645813618. Its totient is φ = 645813616.

The previous prime is 645813583. The next prime is 645813631. The reversal of 645813617 is 716318546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 485056576 + 160757041 = 22024^2 + 12679^2 .

It is a cyclic number.

It is not a de Polignac number, because 645813617 - 2⁸ = 645813361 is a prime.

It is not a weakly prime, because it can be changed into another prime (645812617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322906808 + 322906809.

It is an arithmetic number, because the mean of its divisors is an integer number (322906809).

Almost surely, 2^645813617 is an apocalyptic number.

It is an amenable number.

645813617 is a deficient number, since it is larger than the sum of its proper divisors (1).

645813617 is an equidigital number, since it uses as much as digits as its factorization.

645813617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 41.

The square root of 645813617 is about 25412.8632192439. The cubic root of 645813617 is about 864.3754017283.

The spelling of 645813617 in words is "six hundred forty-five million, eight hundred thirteen thousand, six hundred seventeen".