21212204112440 has 128 divisors (see below), whose sum is σ = 52166321507520. Its totient is φ = 7698721075200.

The previous prime is 21212204112419. The next prime is 21212204112443. The reversal of 21212204112440 is 4421140221212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212204112443) 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, 1149267692 + ... + 1149286148.

Almost surely, 2^{21212204112440} is an apocalyptic number.

21212204112440 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 21212204112440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26083160753760).

21212204112440 is an abundant number, since it is smaller than the sum of its proper divisors (30954117395080).

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

21212204112440 is a wasteful number, since it uses less digits than its factorization.

21212204112440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23353 (or 23349 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 26.

Adding to 21212204112440 its reverse (4421140221212), we get a palindrome (25633344333652).

The spelling of 21212204112440 in words is "twenty-one trillion, two hundred twelve billion, two hundred four million, one hundred twelve thousand, four hundred forty".