644874686 has 16 divisors (see below), whose sum is σ = 989991936. Its totient is φ = 314906616.

The previous prime is 644874673. The next prime is 644874689. The reversal of 644874686 is 686478446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644874689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38735 + ... + 52821.

It is an arithmetic number, because the mean of its divisors is an integer number (61874496).

Almost surely, 2^644874686 is an apocalyptic number.

644874686 is a deficient number, since it is larger than the sum of its proper divisors (345117250).

644874686 is a wasteful number, since it uses less digits than its factorization.

644874686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14623.

The product of its digits is 6193152, while the sum is 53.

The square root of 644874686 is about 25394.3829615921. The cubic root of 644874686 is about 863.9563011949.

The spelling of 644874686 in words is "six hundred forty-four million, eight hundred seventy-four thousand, six hundred eighty-six".