646555220 has 48 divisors (see below), whose sum is σ = 1484034048. Its totient is φ = 235553280.

The previous prime is 646555213. The next prime is 646555229. The reversal of 646555220 is 22555646.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646555229) 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 15 ways as a sum of consecutive naturals, for example, 20132 + ... + 41211.

It is an arithmetic number, because the mean of its divisors is an integer number (30917376).

Almost surely, 2^646555220 is an apocalyptic number.

It is an amenable number.

646555220 is an abundant number, since it is smaller than the sum of its proper divisors (837478828).

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

646555220 is a wasteful number, since it uses less digits than its factorization.

646555220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61400 (or 61398 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 35.

The square root of 646555220 is about 25427.4501277655. The cubic root of 646555220 is about 864.7061360471.

The spelling of 646555220 in words is "six hundred forty-six million, five hundred fifty-five thousand, two hundred twenty".