21019115520 has 960 divisors, whose sum is σ = 87196919040. Its totient is φ = 4756340736.

The previous prime is 21019115419. The next prime is 21019115539. The reversal of 21019115520 is 2551191012.

21019115520 is a `hidden beast` number, since 2 + 10 + 19 + 115 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 488816619 + ... + 488816661.

It is an arithmetic number, because the mean of its divisors is an integer number (90830124).

Almost surely, 2^21019115520 is an apocalyptic number.

21019115520 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 21019115520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43598459520).

21019115520 is an abundant number, since it is smaller than the sum of its proper divisors (66177803520).

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

21019115520 is a wasteful number, since it uses less digits than its factorization.

21019115520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115 (or 83 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 27.

The spelling of 21019115520 in words is "twenty-one billion, nineteen million, one hundred fifteen thousand, five hundred twenty".