1021020521 has 4 divisors (see below), whose sum is σ = 1021103700. Its totient is φ = 1020937344.

The previous prime is 1021020491. The next prime is 1021020529. The reversal of 1021020521 is 1250201201.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1250201201 = 31 ⋅40329071.

It can be written as a sum of positive squares in 2 ways, for example, as 152893225 + 868127296 = 12365^2 + 29464^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021020521 - 2¹⁰ = 1021019497 is a prime.

It is a super-2 number, since 2×1021020521² = 2084965808606222882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1021020496 and 1021020505.

It is not an unprimeable number, because it can be changed into a prime (1021020529) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 19136 + ... + 49073.

It is an arithmetic number, because the mean of its divisors is an integer number (255275925).

Almost surely, 2^1021020521 is an apocalyptic number.

It is an amenable number.

1021020521 is a deficient number, since it is larger than the sum of its proper divisors (83179).

1021020521 is an equidigital number, since it uses as much as digits as its factorization.

1021020521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83178.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 1021020521 is about 31953.4117270754. The cubic root of 1021020521 is about 1006.9583099533.

Adding to 1021020521 its reverse (1250201201), we get a palindrome (2271221722).

The spelling of 1021020521 in words is "one billion, twenty-one million, twenty thousand, five hundred twenty-one".