646983920 has 40 divisors (see below), whose sum is σ = 1640988720. Its totient is φ = 235266560.

The previous prime is 646983817. The next prime is 646983923. The reversal of 646983920 is 29389646.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646983923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 366725 + ... + 368484.

It is an arithmetic number, because the mean of its divisors is an integer number (41024718).

Almost surely, 2^646983920 is an apocalyptic number.

It is an amenable number.

646983920 is an abundant number, since it is smaller than the sum of its proper divisors (994004800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646983920 is a wasteful number, since it uses less digits than its factorization.

646983920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 735233 (or 735227 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 47.

The square root of 646983920 is about 25435.8785969740. The cubic root of 646983920 is about 864.8972089868.

The spelling of 646983920 in words is "six hundred forty-six million, nine hundred eighty-three thousand, nine hundred twenty".