645616841 has 2 divisors, whose sum is σ = 645616842. Its totient is φ = 645616840.

The previous prime is 645616801. The next prime is 645616847. The reversal of 645616841 is 148616546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 510940816 + 134676025 = 22604^2 + 11605^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645616841 is a prime.

It is a super-3 number, since 3×645616841³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645616847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322808420 + 322808421.

It is an arithmetic number, because the mean of its divisors is an integer number (322808421).

Almost surely, 2^645616841 is an apocalyptic number.

It is an amenable number.

645616841 is a deficient number, since it is larger than the sum of its proper divisors (1).

645616841 is an equidigital number, since it uses as much as digits as its factorization.

645616841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 138240, while the sum is 41.

The square root of 645616841 is about 25408.9913416491. The cubic root of 645616841 is about 864.2876026030.

The spelling of 645616841 in words is "six hundred forty-five million, six hundred sixteen thousand, eight hundred forty-one".