664106768640 has 648 divisors, whose sum is σ = 2678004653688. Its totient is φ = 151505141760.

The previous prime is 664106768621. The next prime is 664106768681. The reversal of 664106768640 is 46867601466.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 93078687744 + 571028080896 = 305088^2 + 755664^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 463437364 + ... + 463438796.

It is an arithmetic number, because the mean of its divisors is an integer number (4132723231).

Almost surely, 2^664106768640 is an apocalyptic number.

664106768640 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 664106768640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1339002326844).

664106768640 is an abundant number, since it is smaller than the sum of its proper divisors (2013897885048).

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

664106768640 is a wasteful number, since it uses less digits than its factorization.

664106768640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2295 (or 2271 counting only the distinct ones).

The product of its (nonzero) digits is 6967296, while the sum is 54.

The spelling of 664106768640 in words is "six hundred sixty-four billion, one hundred six million, seven hundred sixty-eight thousand, six hundred forty".