645116569 has 2 divisors, whose sum is σ = 645116570. Its totient is φ = 645116568.

The previous prime is 645116551. The next prime is 645116597. The reversal of 645116569 is 965611546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 537683344 + 107433225 = 23188^2 + 10365^2 .

It is a cyclic number.

It is not a de Polignac number, because 645116569 - 2²⁵ = 611562137 is a prime.

It is a super-4 number, since 4×645116569⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (645110569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322558284 + 322558285.

It is an arithmetic number, because the mean of its divisors is an integer number (322558285).

Almost surely, 2^645116569 is an apocalyptic number.

It is an amenable number.

645116569 is a deficient number, since it is larger than the sum of its proper divisors (1).

645116569 is an equidigital number, since it uses as much as digits as its factorization.

645116569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 194400, while the sum is 43.

The square root of 645116569 is about 25399.1450446664. The cubic root of 645116569 is about 864.0643067884.

The spelling of 645116569 in words is "six hundred forty-five million, one hundred sixteen thousand, five hundred sixty-nine".