661544485200 has 720 divisors, whose sum is σ = 2571188558400. Its totient is φ = 161336448000.

The previous prime is 661544485163. The next prime is 661544485201. The reversal of 661544485200 is 2584445166.

It is a happy number.

661544485200 is a `hidden beast` number, since 6 + 6 + 1 + 544 + 4 + 85 + 20 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a super-2 number, since 2×661544485200² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661544485201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 113062275 + ... + 113068125.

It is an arithmetic number, because the mean of its divisors is an integer number (3571095220).

Almost surely, 2^661544485200 is an apocalyptic number.

661544485200 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 661544485200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1285594279200).

661544485200 is an abundant number, since it is smaller than the sum of its proper divisors (1909644073200).

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

661544485200 is a wasteful number, since it uses less digits than its factorization.

661544485200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5945 (or 5909 counting only the distinct ones).

The product of its (nonzero) digits is 921600, while the sum is 45.

The spelling of 661544485200 in words is "six hundred sixty-one billion, five hundred forty-four million, four hundred eighty-five thousand, two hundred".