1661031187200 has 1728 divisors, whose sum is σ = 7840671498240. Its totient is φ = 333932544000.

The previous prime is 1661031187199. The next prime is 1661031187331. The reversal of 1661031187200 is 27811301661.

1661031187200 is a `hidden beast` number, since 1 + 6 + 61 + 0 + 311 + 87 + 200 = 666.

It is a tau number, because it is divible by the number of its divisors (1728).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 412471587 + ... + 412475613.

Almost surely, 2^{1661031187200} is an apocalyptic number.

1661031187200 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 1661031187200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3920335749120).

1661031187200 is an abundant number, since it is smaller than the sum of its proper divisors (6179640311040).

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

1661031187200 is a wasteful number, since it uses less digits than its factorization.

1661031187200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4111 (or 4086 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

Adding to 1661031187200 its reverse (27811301661), we get a palindrome (1688842488861).

The spelling of 1661031187200 in words is "one trillion, six hundred sixty-one billion, thirty-one million, one hundred eighty-seven thousand, two hundred".