21798400212 has 120 divisors (see below), whose sum is σ = 60744637800. Its totient is φ = 6792560640.

The previous prime is 21798400193. The next prime is 21798400223. The reversal of 21798400212 is 21200489712.

It can be written as a sum of positive squares in 4 ways, for example, as 5451754896 + 16346645316 = 73836^2 + 127854^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 807412 + ... + 833972.

It is an arithmetic number, because the mean of its divisors is an integer number (506205315).

Almost surely, 2^21798400212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21798400212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30372318900).

21798400212 is an abundant number, since it is smaller than the sum of its proper divisors (38946237588).

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

21798400212 is a wasteful number, since it uses less digits than its factorization.

21798400212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26743 (or 26732 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

Adding to 21798400212 its reverse (21200489712), we get a palindrome (42998889924).

The spelling of 21798400212 in words is "twenty-one billion, seven hundred ninety-eight million, four hundred thousand, two hundred twelve".