21018580800 has 336 divisors, whose sum is σ = 79634486400. Its totient is φ = 4753981440.

The previous prime is 21018580799. The next prime is 21018580811. The reversal of 21018580800 is 808581012.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-2 number, since 2×21018580800² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3255976 + ... + 3262424.

It is an arithmetic number, because the mean of its divisors is an integer number (237007400).

Almost surely, 2^21018580800 is an apocalyptic number.

21018580800 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 21018580800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39817243200).

21018580800 is an abundant number, since it is smaller than the sum of its proper divisors (58615905600).

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

21018580800 is a wasteful number, since it uses less digits than its factorization.

21018580800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6578 (or 6563 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 33.

The spelling of 21018580800 in words is "twenty-one billion, eighteen million, five hundred eighty thousand, eight hundred".