6666691664400 has 240 divisors, whose sum is σ = 22614367320000. Its totient is φ = 1673022586880.

The previous prime is 6666691664393. The next prime is 6666691664411. The reversal of 6666691664400 is 44661966666.

It is a tau number, because it is divible by the number of its divisors (240).

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

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 47 ways as a sum of consecutive naturals, for example, 329225476 + ... + 329245724.

It is an arithmetic number, because the mean of its divisors is an integer number (94226530500).

Almost surely, 2^{6666691664400} is an apocalyptic number.

6666691664400 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 6666691664400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11307183660000).

6666691664400 is an abundant number, since it is smaller than the sum of its proper divisors (15947675655600).

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

6666691664400 is a wasteful number, since it uses less digits than its factorization.

6666691664400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36426 (or 36415 counting only the distinct ones).

The product of its (nonzero) digits is 40310784, while the sum is 60.

The spelling of 6666691664400 in words is "six trillion, six hundred sixty-six billion, six hundred ninety-one million, six hundred sixty-four thousand, four hundred".