21020521040 has 80 divisors (see below), whose sum is σ = 49658071680. Its totient is φ = 8273379840.

The previous prime is 21020521019. The next prime is 21020521051. The reversal of 21020521040 is 4012502012.

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

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 6585845 + ... + 6589035.

It is an arithmetic number, because the mean of its divisors is an integer number (620725896).

Almost surely, 2^21020521040 is an apocalyptic number.

21020521040 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 21020521040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24829035840).

21020521040 is an abundant number, since it is smaller than the sum of its proper divisors (28637550640).

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

21020521040 is a wasteful number, since it uses less digits than its factorization.

21020521040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4500 (or 4494 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The spelling of 21020521040 in words is "twenty-one billion, twenty million, five hundred twenty-one thousand, forty".