21043040040 has 192 divisors, whose sum is σ = 74672020800. Its totient is φ = 5096908800.

The previous prime is 21043040027. The next prime is 21043040041. The reversal of 21043040040 is 4004034012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21043039995 and 21043040022.

It is not an unprimeable number, because it can be changed into a prime (21043040041) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8556331 + ... + 8558789.

It is an arithmetic number, because the mean of its divisors is an integer number (388916775).

Almost surely, 2^21043040040 is an apocalyptic number.

21043040040 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 21043040040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37336010400).

21043040040 is an abundant number, since it is smaller than the sum of its proper divisors (53628980760).

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

21043040040 is a wasteful number, since it uses less digits than its factorization.

21043040040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4648 (or 4641 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

Adding to 21043040040 its reverse (4004034012), we get a palindrome (25047074052).

The spelling of 21043040040 in words is "twenty-one billion, forty-three million, forty thousand, forty".