21120240343440 has 640 divisors, whose sum is σ = 79944743780352. Its totient is φ = 4507405056000.

The previous prime is 21120240343379. The next prime is 21120240343441. The reversal of 21120240343440 is 4434304202112.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21120240343398 and 21120240343407.

It is not an unprimeable number, because it can be changed into a prime (21120240343441) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3740078697 + ... + 3740084343.

Almost surely, 2^{21120240343440} is an apocalyptic number.

21120240343440 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 21120240343440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39972371890176).

21120240343440 is an abundant number, since it is smaller than the sum of its proper divisors (58824503436912).

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

21120240343440 is a wasteful number, since it uses less digits than its factorization.

21120240343440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7987 (or 7981 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 30.

Adding to 21120240343440 its reverse (4434304202112), we get a palindrome (25554544545552).

The spelling of 21120240343440 in words is "twenty-one trillion, one hundred twenty billion, two hundred forty million, three hundred forty-three thousand, four hundred forty".