646656020 has 24 divisors (see below), whose sum is σ = 1363622568. Its totient is φ = 257587200.

The previous prime is 646656019. The next prime is 646656037. The reversal of 646656020 is 20656646.

It can be written as a sum of positive squares in 4 ways, for example, as 69022864 + 577633156 = 8308^2 + 24034^2 .

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, 62261 + ... + 71900.

It is an arithmetic number, because the mean of its divisors is an integer number (56817607).

Almost surely, 2^646656020 is an apocalyptic number.

It is an amenable number.

646656020 is an abundant number, since it is smaller than the sum of its proper divisors (716966548).

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

646656020 is a wasteful number, since it uses less digits than its factorization.

646656020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134411 (or 134409 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 35.

The square root of 646656020 is about 25429.4321603924. The cubic root of 646656020 is about 864.7510705175.

The spelling of 646656020 in words is "six hundred forty-six million, six hundred fifty-six thousand, twenty".