21861204480 has 320 divisors, whose sum is σ = 77957510400. Its totient is φ = 5806817280.

The previous prime is 21861204437. The next prime is 21861204493. The reversal of 21861204480 is 8440216812.

It is a tau number, because it is divible by the number of its divisors (320).

It is a super-2 number, since 2×21861204480² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24813640 + ... + 24814520.

It is an arithmetic number, because the mean of its divisors is an integer number (243617220).

Almost surely, 2^21861204480 is an apocalyptic number.

21861204480 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 21861204480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38978755200).

21861204480 is an abundant number, since it is smaller than the sum of its proper divisors (56096305920).

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

21861204480 is an equidigital number, since it uses as much as digits as its factorization.

21861204480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1272 (or 1250 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The spelling of 21861204480 in words is "twenty-one billion, eight hundred sixty-one million, two hundred four thousand, four hundred eighty".