21050005520 has 80 divisors (see below), whose sum is σ = 49732745472. Its totient is φ = 8284400640.

The previous prime is 21050005507. The next prime is 21050005541. The reversal of 21050005520 is 2550005012.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21050005492 and 21050005501.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2512859 + ... + 2521221.

Almost surely, 2^21050005520 is an apocalyptic number.

21050005520 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 21050005520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24866372736).

21050005520 is an abundant number, since it is smaller than the sum of its proper divisors (28682739952).

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

21050005520 is a wasteful number, since it uses less digits than its factorization.

21050005520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8880 (or 8874 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 20.

The spelling of 21050005520 in words is "twenty-one billion, fifty million, five thousand, five hundred twenty".