646647555840 has 1152 divisors, whose sum is σ = 2619482084352. Its totient is φ = 133520424960.

The previous prime is 646647555811. The next prime is 646647555877. The reversal of 646647555840 is 48555746646.

It is a super-2 number, since 2×646647555840² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (60).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 494756467 + ... + 494757773.

It is an arithmetic number, because the mean of its divisors is an integer number (2273855976).

Almost surely, 2^646647555840 is an apocalyptic number.

646647555840 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 646647555840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1309741042176).

646647555840 is an abundant number, since it is smaller than the sum of its proper divisors (1972834528512).

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

646647555840 is a wasteful number, since it uses less digits than its factorization.

646647555840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1425 (or 1411 counting only the distinct ones).

The product of its (nonzero) digits is 96768000, while the sum is 60.

The spelling of 646647555840 in words is "six hundred forty-six billion, six hundred forty-seven million, five hundred fifty-five thousand, eight hundred forty".