646622720 has 80 divisors (see below), whose sum is σ = 1558560960. Its totient is φ = 257286144.

The previous prime is 646622719. The next prime is 646622747. The reversal of 646622720 is 27226646.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

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, 585689 + ... + 586791.

It is an arithmetic number, because the mean of its divisors is an integer number (19482012).

Almost surely, 2^646622720 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646622720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (779280480).

646622720 is an abundant number, since it is smaller than the sum of its proper divisors (911938240).

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

646622720 is a wasteful number, since it uses less digits than its factorization.

646622720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1355 (or 1339 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 35.

The square root of 646622720 is about 25428.7773988448. Note that the first 3 decimals coincide. The cubic root of 646622720 is about 864.7362266108.

The spelling of 646622720 in words is "six hundred forty-six million, six hundred twenty-two thousand, seven hundred twenty".