21661486560 has 1152 divisors, whose sum is σ = 95103590400. Its totient is φ = 4546160640.

The previous prime is 21661486559. The next prime is 21661486633. The reversal of 21661486560 is 6568416612.

21661486560 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 1 + 4 + 86 + 560 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 305091325 + ... + 305091395.

It is an arithmetic number, because the mean of its divisors is an integer number (82555200).

Almost surely, 2^21661486560 is an apocalyptic number.

21661486560 is a gapful number since it is divisible by the number (20) 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 21661486560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47551795200).

21661486560 is an abundant number, since it is smaller than the sum of its proper divisors (73442103840).

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

21661486560 is a wasteful number, since it uses less digits than its factorization.

21661486560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186 (or 166 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The spelling of 21661486560 in words is "twenty-one billion, six hundred sixty-one million, four hundred eighty-six thousand, five hundred sixty".