645220343253 has 4 divisors (see below), whose sum is σ = 860293791008. Its totient is φ = 430146895500.

The previous prime is 645220343219. The next prime is 645220343267. The reversal of 645220343253 is 352343022546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 645220343253 - 2⁸ = 645220342997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645220347253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107536723873 + ... + 107536723878.

It is an arithmetic number, because the mean of its divisors is an integer number (215073447752).

Almost surely, 2^645220343253 is an apocalyptic number.

It is an amenable number.

645220343253 is a deficient number, since it is larger than the sum of its proper divisors (215073447755).

645220343253 is a wasteful number, since it uses less digits than its factorization.

645220343253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215073447754.

The product of its (nonzero) digits is 518400, while the sum is 39.

Adding to 645220343253 its reverse (352343022546), we get a palindrome (997563365799).

The spelling of 645220343253 in words is "six hundred forty-five billion, two hundred twenty million, three hundred forty-three thousand, two hundred fifty-three".