6661490378400 has 1728 divisors, whose sum is σ = 30165115309056. Its totient is φ = 1357627392000.

The previous prime is 6661490378377. The next prime is 6661490378401. The reversal of 6661490378400 is 48730941666.

It is not an unprimeable number, because it can be changed into a prime (6661490378401) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 542593062 + ... + 542605338.

It is an arithmetic number, because the mean of its divisors is an integer number (17456663952).

Almost surely, 2^{6661490378400} is an apocalyptic number.

6661490378400 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 6661490378400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15082557654528).

6661490378400 is an abundant number, since it is smaller than the sum of its proper divisors (23503624930656).

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

6661490378400 is a wasteful number, since it uses less digits than its factorization.

6661490378400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12375 (or 12359 counting only the distinct ones).

The product of its (nonzero) digits is 5225472, while the sum is 54.

The spelling of 6661490378400 in words is "six trillion, six hundred sixty-one billion, four hundred ninety million, three hundred seventy-eight thousand, four hundred".