646566665580 has 384 divisors, whose sum is σ = 2241048821760. Its totient is φ = 153441319680.

The previous prime is 646566665579. The next prime is 646566665683. The reversal of 646566665580 is 85566665646.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 64865757 + ... + 64875723.

It is an arithmetic number, because the mean of its divisors is an integer number (5836064640).

Almost surely, 2^646566665580 is an apocalyptic number.

646566665580 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646566665580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1120524410880).

646566665580 is an abundant number, since it is smaller than the sum of its proper divisors (1594482156180).

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

646566665580 is a wasteful number, since it uses less digits than its factorization.

646566665580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10226 (or 10218 counting only the distinct ones).

The product of its (nonzero) digits is 186624000, while the sum is 63.

The spelling of 646566665580 in words is "six hundred forty-six billion, five hundred sixty-six million, six hundred sixty-five thousand, five hundred eighty".