21555522040 has 256 divisors, whose sum is σ = 56899584000. Its totient is φ = 7280824320.

The previous prime is 21555521963. The next prime is 21555522041. The reversal of 21555522040 is 4022555512.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21555521993 and 21555522011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21555522041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 51444951 + ... + 51445369.

It is an arithmetic number, because the mean of its divisors is an integer number (222264000).

Almost surely, 2^21555522040 is an apocalyptic number.

21555522040 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 21555522040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28449792000).

21555522040 is an abundant number, since it is smaller than the sum of its proper divisors (35344061960).

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

21555522040 is a wasteful number, since it uses less digits than its factorization.

21555522040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 630 (or 626 counting only the distinct ones).

The product of its (nonzero) digits is 20000, while the sum is 31.

The spelling of 21555522040 in words is "twenty-one billion, five hundred fifty-five million, five hundred twenty-two thousand, forty".