21181858560 has 576 divisors, whose sum is σ = 82225704960. Its totient is φ = 5140316160.

The previous prime is 21181858549. The next prime is 21181858561. The reversal of 21181858560 is 6585818112.

21181858560 is a `hidden beast` number, since 2 + 1 + 1 + 8 + 1 + 8 + 585 + 60 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

It is a super-2 number, since 2×21181858560² (a number of 21 digits) contains 22 as substring.

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 (21181858561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 18212539 + ... + 18213701.

It is an arithmetic number, because the mean of its divisors is an integer number (142752960).

Almost surely, 2^21181858560 is an apocalyptic number.

21181858560 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 21181858560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41112852480).

21181858560 is an abundant number, since it is smaller than the sum of its proper divisors (61043846400).

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

21181858560 is a wasteful number, since it uses less digits than its factorization.

21181858560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1241 (or 1221 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 45.

The spelling of 21181858560 in words is "twenty-one billion, one hundred eighty-one million, eight hundred fifty-eight thousand, five hundred sixty".