661321221120 has 880 divisors, whose sum is σ = 2734940039040. Its totient is φ = 149676097536.

The previous prime is 661321221103. The next prime is 661321221173. The reversal of 661321221120 is 21122123166.

661321221120 is a `hidden beast` number, since 6 + 613 + 2 + 1 + 2 + 21 + 1 + 20 = 666.

661321221120 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 310624216 + ... + 310626344.

It is an arithmetic number, because the mean of its divisors is an integer number (3107886408).

Almost surely, 2^661321221120 is an apocalyptic number.

661321221120 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 661321221120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1367470019520).

661321221120 is an abundant number, since it is smaller than the sum of its proper divisors (2073618817920).

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

661321221120 is a wasteful number, since it uses less digits than its factorization.

661321221120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2280 (or 2253 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

Adding to 661321221120 its reverse (21122123166), we get a palindrome (682443344286).

The spelling of 661321221120 in words is "six hundred sixty-one billion, three hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty".