21201040440 has 512 divisors, whose sum is σ = 75771936000. Its totient is φ = 5329981440.

The previous prime is 21201040429. The next prime is 21201040447. The reversal of 21201040440 is 4404010212.

21201040440 is a `hidden beast` number, since 2 + 120 + 104 + 0 + 440 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201040447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 154752052 + ... + 154752188.

Almost surely, 2^21201040440 is an apocalyptic number.

21201040440 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 21201040440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37885968000).

21201040440 is an abundant number, since it is smaller than the sum of its proper divisors (54570895560).

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

21201040440 is a wasteful number, since it uses less digits than its factorization.

21201040440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259 (or 237 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

Adding to 21201040440 its reverse (4404010212), we get a palindrome (25605050652).

The spelling of 21201040440 in words is "twenty-one billion, two hundred one million, forty thousand, four hundred forty".