645739117 has 2 divisors, whose sum is σ = 645739118. Its totient is φ = 645739116.

The previous prime is 645739109. The next prime is 645739123. The reversal of 645739117 is 711937546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 624450121 + 21288996 = 24989^2 + 4614^2 .

It is a cyclic number.

It is not a de Polignac number, because 645739117 - 2³ = 645739109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645739147) 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, 322869558 + 322869559.

It is an arithmetic number, because the mean of its divisors is an integer number (322869559).

Almost surely, 2^645739117 is an apocalyptic number.

It is an amenable number.

645739117 is a deficient number, since it is larger than the sum of its proper divisors (1).

645739117 is an equidigital number, since it uses as much as digits as its factorization.

645739117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 158760, while the sum is 43.

The square root of 645739117 is about 25411.3973838512. The cubic root of 645739117 is about 864.3421628071.

The spelling of 645739117 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, one hundred seventeen".