661885344000 has 1008 divisors, whose sum is σ = 2619115415280. Its totient is φ = 166020710400.

The previous prime is 661885343989. The next prime is 661885344007. The reversal of 661885344000 is 443588166.

661885344000 is a `hidden beast` number, since 66 + 18 + 8 + 534 + 40 + 0 + 0 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 120636739584 + 541248604416 = 347328^2 + 735696^2 .

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

It is not an unprimeable number, because it can be changed into a prime (661885344007) by changing a digit.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 396575166 + ... + 396576834.

It is an arithmetic number, because the mean of its divisors is an integer number (2598328785).

Almost surely, 2^661885344000 is an apocalyptic number.

661885344000 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 661885344000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1309557707640).

661885344000 is an abundant number, since it is smaller than the sum of its proper divisors (1957230071280).

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

661885344000 is an equidigital number, since it uses as much as digits as its factorization.

661885344000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1735 (or 1696 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 45.

The spelling of 661885344000 in words is "six hundred sixty-one billion, eight hundred eighty-five million, three hundred forty-four thousand".