646338631680 has 2304 divisors, whose sum is σ = 2939908608000. Its totient is φ = 135444234240.

The previous prime is 646338631669. The next prime is 646338631691. The reversal of 646338631680 is 86136833646.

646338631680 is a `hidden beast` number, since 6 + 463 + 38 + 63 + 16 + 80 = 666.

It is an interprime number because it is at equal distance from previous prime (646338631669) and next prime (646338631691).

It is a tau number, because it is divible by the number of its divisors (2304).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 20849633265 + ... + 20849633295.

It is an arithmetic number, because the mean of its divisors is an integer number (1276002000).

Almost surely, 2^646338631680 is an apocalyptic number.

646338631680 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 646338631680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1469954304000).

646338631680 is an abundant number, since it is smaller than the sum of its proper divisors (2293569976320).

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

646338631680 is an equidigital number, since it uses as much as digits as its factorization.

646338631680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112 (or 67 counting only the distinct ones).

The product of its (nonzero) digits is 8957952, while the sum is 54.

The spelling of 646338631680 in words is "six hundred forty-six billion, three hundred thirty-eight million, six hundred thirty-one thousand, six hundred eighty".