645643275 has 48 divisors (see below), whose sum is σ = 1128320640. Its totient is φ = 324864000.

The previous prime is 645643267. The next prime is 645643279. The reversal of 645643275 is 572346546.

It is not a de Polignac number, because 645643275 - 2³ = 645643267 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645643279) 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 in 47 ways as a sum of consecutive naturals, for example, 402475 + ... + 404075.

It is an arithmetic number, because the mean of its divisors is an integer number (23506680).

Almost surely, 2^645643275 is an apocalyptic number.

645643275 is a deficient number, since it is larger than the sum of its proper divisors (482677365).

645643275 is a wasteful number, since it uses less digits than its factorization.

645643275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1916 (or 1911 counting only the distinct ones).

The product of its digits is 604800, while the sum is 42.

The square root of 645643275 is about 25409.5115065205. The cubic root of 645643275 is about 864.2993981786.

The spelling of 645643275 in words is "six hundred forty-five million, six hundred forty-three thousand, two hundred seventy-five".