1661221342000 has 240 divisors, whose sum is σ = 4418825052096. Its totient is φ = 603584256000.

The previous prime is 1661221341917. The next prime is 1661221342003. The reversal of 1661221342000 is 2431221661.

It is a self number, because there is not a number n which added to its sum of digits gives 1661221342000.

It is not an unprimeable number, because it can be changed into a prime (1661221342003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 430032069 + ... + 430035931.

Almost surely, 2^{1661221342000} is an apocalyptic number.

1661221342000 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 1661221342000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2209412526048).

1661221342000 is an abundant number, since it is smaller than the sum of its proper divisors (2757603710096).

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

1661221342000 is a wasteful number, since it uses less digits than its factorization.

1661221342000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5685 (or 5658 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

Adding to 1661221342000 its reverse (2431221661), we get a palindrome (1663652563661).

The spelling of 1661221342000 in words is "one trillion, six hundred sixty-one billion, two hundred twenty-one million, three hundred forty-two thousand".