21815505120 has 192 divisors, whose sum is σ = 72860256000. Its totient is φ = 5471318016.

The previous prime is 21815505001. The next prime is 21815505121. The reversal of 21815505120 is 2150551812.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21815505121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1259076 + ... + 1276284.

It is an arithmetic number, because the mean of its divisors is an integer number (379480500).

Almost surely, 2^21815505120 is an apocalyptic number.

21815505120 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 21815505120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36430128000).

21815505120 is an abundant number, since it is smaller than the sum of its proper divisors (51044750880).

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

21815505120 is a wasteful number, since it uses less digits than its factorization.

21815505120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17385 (or 17377 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 30.

The spelling of 21815505120 in words is "twenty-one billion, eight hundred fifteen million, five hundred five thousand, one hundred twenty".