1666243781400 has 768 divisors, whose sum is σ = 6091632967680. Its totient is φ = 372556800000.

The previous prime is 1666243781399. The next prime is 1666243781429. The reversal of 1666243781400 is 41873426661.

It is a self number, because there is not a number n which added to its sum of digits gives 1666243781400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1887025359 + ... + 1887026241.

It is an arithmetic number, because the mean of its divisors is an integer number (7931813760).

Almost surely, 2^{1666243781400} is an apocalyptic number.

1666243781400 is a gapful number since it is divisible by the number (10) 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 1666243781400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3045816483840).

1666243781400 is an abundant number, since it is smaller than the sum of its proper divisors (4425389186280).

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

1666243781400 is a wasteful number, since it uses less digits than its factorization.

1666243781400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1368 (or 1359 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 48.

The spelling of 1666243781400 in words is "one trillion, six hundred sixty-six billion, two hundred forty-three million, seven hundred eighty-one thousand, four hundred".