21012220218 has 64 divisors (see below), whose sum is σ = 49087244160. Its totient is φ = 5925427200.

The previous prime is 21012220211. The next prime is 21012220223. The reversal of 21012220218 is 81202221012.

It is a junction number, because it is equal to n+sod(n) for n = 21012220194 and 21012220203.

It is not an unprimeable number, because it can be changed into a prime (21012220211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5353 + ... + 205068.

It is an arithmetic number, because the mean of its divisors is an integer number (766988190).

Almost surely, 2^21012220218 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21012220218, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24543622080).

21012220218 is an abundant number, since it is smaller than the sum of its proper divisors (28075023942).

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

21012220218 is a wasteful number, since it uses less digits than its factorization.

21012220218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210543.

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

The spelling of 21012220218 in words is "twenty-one billion, twelve million, two hundred twenty thousand, two hundred eighteen".