21001322043240 has 256 divisors, whose sum is σ = 78590280222720. Its totient is φ = 4361695472640.

The previous prime is 21001322043217. The next prime is 21001322043301. The reversal of 21001322043240 is 4234022310012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21001322043240.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 17654527 + ... + 18806513.

It is an arithmetic number, because the mean of its divisors is an integer number (306993282120).

Almost surely, 2^{21001322043240} is an apocalyptic number.

21001322043240 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 21001322043240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39295140111360).

21001322043240 is an abundant number, since it is smaller than the sum of its proper divisors (57588958179480).

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

21001322043240 is a wasteful number, since it uses less digits than its factorization.

21001322043240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1153992 (or 1153988 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

Adding to 21001322043240 its reverse (4234022310012), we get a palindrome (25235344353252).

The spelling of 21001322043240 in words is "twenty-one trillion, one billion, three hundred twenty-two million, forty-three thousand, two hundred forty".