645554871 has 24 divisors (see below), whose sum is σ = 1007872320. Its totient is φ = 395810496.

The previous prime is 645554839. The next prime is 645554909. The reversal of 645554871 is 178455546.

It is not a de Polignac number, because 645554871 - 2⁵ = 645554839 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645554831) 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 23 ways as a sum of consecutive naturals, for example, 22450 + ... + 42368.

It is an arithmetic number, because the mean of its divisors is an integer number (41994680).

Almost surely, 2^645554871 is an apocalyptic number.

645554871 is a deficient number, since it is larger than the sum of its proper divisors (362317449).

645554871 is a wasteful number, since it uses less digits than its factorization.

645554871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20215 (or 20212 counting only the distinct ones).

The product of its digits is 672000, while the sum is 45.

The square root of 645554871 is about 25407.7718621685. The cubic root of 645554871 is about 864.2599486278.

The spelling of 645554871 in words is "six hundred forty-five million, five hundred fifty-four thousand, eight hundred seventy-one".