645523314209 has 2 divisors, whose sum is σ = 645523314210. Its totient is φ = 645523314208.

The previous prime is 645523314179. The next prime is 645523314211. The reversal of 645523314209 is 902413325546.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 541258904209 + 104264410000 = 735703^2 + 322900^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645523314209 is a prime.

It is a Sophie Germain prime.

Together with 645523314211, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 645523314209.

It is not a weakly prime, because it can be changed into another prime (645523313209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322761657104 + 322761657105.

It is an arithmetic number, because the mean of its divisors is an integer number (322761657105).

Almost surely, 2^645523314209 is an apocalyptic number.

It is an amenable number.

645523314209 is a deficient number, since it is larger than the sum of its proper divisors (1).

645523314209 is an equidigital number, since it uses as much as digits as its factorization.

645523314209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 777600, while the sum is 44.

The spelling of 645523314209 in words is "six hundred forty-five billion, five hundred twenty-three million, three hundred fourteen thousand, two hundred nine".