21518920208040 has 128 divisors (see below), whose sum is σ = 64795618258560. Its totient is φ = 5717150659584.

The previous prime is 21518920208033. The next prime is 21518920208041. The reversal of 21518920208040 is 4080202981512.

It is a junction number, because it is equal to n+sod(n) for n = 21518920207983 and 21518920208001.

It is not an unprimeable number, because it can be changed into a prime (21518920208041) 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 31 ways as a sum of consecutive naturals, for example, 502135254 + ... + 502178106.

It is an arithmetic number, because the mean of its divisors is an integer number (506215767645).

Almost surely, 2^{21518920208040} is an apocalyptic number.

21518920208040 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 21518920208040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32397809129280).

21518920208040 is an abundant number, since it is smaller than the sum of its proper divisors (43276698050520).

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

21518920208040 is a wasteful number, since it uses less digits than its factorization.

21518920208040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58251 (or 58247 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 42.

The spelling of 21518920208040 in words is "twenty-one trillion, five hundred eighteen billion, nine hundred twenty million, two hundred eight thousand, forty".