64640002820 has 24 divisors (see below), whose sum is σ = 135825408600. Its totient is φ = 25840495872.

The previous prime is 64640002807. The next prime is 64640002859. The reversal of 64640002820 is 2820004646.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9020440576 + 55619562244 = 94976^2 + 235838^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 934865 + ... + 1001624.

It is an arithmetic number, because the mean of its divisors is an integer number (5659392025).

Almost surely, 2^64640002820 is an apocalyptic number.

It is an amenable number.

64640002820 is an abundant number, since it is smaller than the sum of its proper divisors (71185405780).

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

64640002820 is a wasteful number, since it uses less digits than its factorization.

64640002820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1938167 (or 1938165 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 32.

The spelling of 64640002820 in words is "sixty-four billion, six hundred forty million, two thousand, eight hundred twenty".