21120012228 has 96 divisors (see below), whose sum is σ = 57334394880. Its totient is φ = 5926314240.

The previous prime is 21120012197. The next prime is 21120012253. The reversal of 21120012228 is 82221002112.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1458343 + ... + 1472753.

It is an arithmetic number, because the mean of its divisors is an integer number (597233280).

Almost surely, 2^21120012228 is an apocalyptic number.

21120012228 is a gapful number since it is divisible by the number (28) 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 21120012228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28667197440).

21120012228 is an abundant number, since it is smaller than the sum of its proper divisors (36214382652).

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

21120012228 is a wasteful number, since it uses less digits than its factorization.

21120012228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14737 (or 14735 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The spelling of 21120012228 in words is "twenty-one billion, one hundred twenty million, twelve thousand, two hundred twenty-eight".