561981385728 has 528 divisors, whose sum is σ = 1907476480000. Its totient is φ = 159286321152.

The previous prime is 561981385697. The next prime is 561981385729. The reversal of 561981385728 is 827583189165.

561981385728 is a `hidden beast` number, since 5 + 619 + 8 + 1 + 3 + 8 + 5 + 7 + 2 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (561981385729) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 439390593 + ... + 439391871.

Almost surely, 2^561981385728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 561981385728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (953738240000).

561981385728 is an abundant number, since it is smaller than the sum of its proper divisors (1345495094272).

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

561981385728 is a wasteful number, since it uses less digits than its factorization.

561981385728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1465 (or 1430 counting only the distinct ones).

The product of its digits is 29030400, while the sum is 63.

The spelling of 561981385728 in words is "five hundred sixty-one billion, nine hundred eighty-one million, three hundred eighty-five thousand, seven hundred twenty-eight".