6661354521600 has 891 divisors, whose sum is σ = 25261436520333. Its totient is φ = 1676921978880.

The previous prime is 6661354521589. The next prime is 6661354521673. The reversal of 6661354521600 is 61254531666.

The square root of 6661354521600 is 2580960.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 2398087627776 + 4263266893824 = 1548576^2 + 2064768^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 23538355059 + ... + 23538355341.

Almost surely, 2^{6661354521600} is an apocalyptic number.

6661354521600 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

6661354521600 is the 2580960-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6661354521600

6661354521600 is an abundant number, since it is smaller than the sum of its proper divisors (18600081998733).

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

6661354521600 is a wasteful number, since it uses less digits than its factorization.

6661354521600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640 (or 312 counting only the distinct ones).

The product of its (nonzero) digits is 777600, while the sum is 45.

The spelling of 6661354521600 in words is "six trillion, six hundred sixty-one billion, three hundred fifty-four million, five hundred twenty-one thousand, six hundred".