641443779648 has 336 divisors, whose sum is σ = 2182470477824. Its totient is φ = 182982965760.

The previous prime is 641443779583. The next prime is 641443779649. The reversal of 641443779648 is 846977344146.

641443779648 is a `hidden beast` number, since 64 + 1 + 443 + 7 + 7 + 96 + 48 = 666.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-2 number, since 2×641443779648² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (641443779649) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 75220761 + ... + 75229287.

Almost surely, 2^641443779648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 641443779648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1091235238912).

641443779648 is an abundant number, since it is smaller than the sum of its proper divisors (1541026698176).

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

641443779648 is an equidigital number, since it uses as much as digits as its factorization.

641443779648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9252 (or 9230 counting only the distinct ones).

The product of its digits is 97542144, while the sum is 63.

The spelling of 641443779648 in words is "six hundred forty-one billion, four hundred forty-three million, seven hundred seventy-nine thousand, six hundred forty-eight".