20520521021 has 64 divisors (see below), whose sum is σ = 28622340096. Its totient is φ = 14192755200.

The previous prime is 20520521009. The next prime is 20520521023. The reversal of 20520521021 is 12012502502.

It is a happy number.

It is not a de Polignac number, because 20520521021 - 2¹⁰ = 20520519997 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20520520984 and 20520521002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20520521023) 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 63 ways as a sum of consecutive naturals, for example, 5056025 + ... + 5060081.

It is an arithmetic number, because the mean of its divisors is an integer number (447224064).

Almost surely, 2^20520521021 is an apocalyptic number.

It is an amenable number.

20520521021 is a deficient number, since it is larger than the sum of its proper divisors (8101819075).

20520521021 is a wasteful number, since it uses less digits than its factorization.

20520521021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4282.

The product of its (nonzero) digits is 400, while the sum is 20.

The spelling of 20520521021 in words is "twenty billion, five hundred twenty million, five hundred twenty-one thousand, twenty-one".