21280105800 has 288 divisors, whose sum is σ = 72859176000. Its totient is φ = 5564966400.

The previous prime is 21280105799. The next prime is 21280105801. The reversal of 21280105800 is 850108212.

21280105800 is a `hidden beast` number, since 2 + 1 + 2 + 80 + 1 + 0 + 580 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21280105799) and next prime (21280105801).

It is not an unprimeable number, because it can be changed into a prime (21280105801) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 34377891 + ... + 34378509.

It is an arithmetic number, because the mean of its divisors is an integer number (252983250).

Almost surely, 2^21280105800 is an apocalyptic number.

21280105800 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 21280105800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36429588000).

21280105800 is an abundant number, since it is smaller than the sum of its proper divisors (51579070200).

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

21280105800 is a wasteful number, since it uses less digits than its factorization.

21280105800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 981 (or 969 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The spelling of 21280105800 in words is "twenty-one billion, two hundred eighty million, one hundred five thousand, eight hundred".