21110821280 has 96 divisors (see below), whose sum is σ = 51323424768. Its totient is φ = 8200857600.

The previous prime is 21110821279. The next prime is 21110821297. The reversal of 21110821280 is 8212801112.

It is a super-2 number, since 2×21110821280² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1455665 + ... + 1470095.

It is an arithmetic number, because the mean of its divisors is an integer number (534619008).

Almost surely, 2^21110821280 is an apocalyptic number.

21110821280 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 21110821280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25661712384).

21110821280 is an abundant number, since it is smaller than the sum of its proper divisors (30212603488).

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

21110821280 is a wasteful number, since it uses less digits than its factorization.

21110821280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14710 (or 14702 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 26.

The spelling of 21110821280 in words is "twenty-one billion, one hundred ten million, eight hundred twenty-one thousand, two hundred eighty".