21011300521 has 4 divisors (see below), whose sum is σ = 21024866500. Its totient is φ = 20997734544.

The previous prime is 21011300507. The next prime is 21011300533. The reversal of 21011300521 is 12500311012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15603757225 + 5407543296 = 124915^2 + 73536^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011300521 - 2²⁹ = 20474429609 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011300495 and 21011300504.

It is not an unprimeable number, because it can be changed into a prime (21011300551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6780666 + ... + 6783763.

It is an arithmetic number, because the mean of its divisors is an integer number (5256216625).

Almost surely, 2^21011300521 is an apocalyptic number.

It is an amenable number.

21011300521 is a deficient number, since it is larger than the sum of its proper divisors (13565979).

21011300521 is a wasteful number, since it uses less digits than its factorization.

21011300521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13565978.

The product of its (nonzero) digits is 60, while the sum is 16.

Adding to 21011300521 its reverse (12500311012), we get a palindrome (33511611533).

The spelling of 21011300521 in words is "twenty-one billion, eleven million, three hundred thousand, five hundred twenty-one".