21010535521 has 4 divisors (see below), whose sum is σ = 22116353200. Its totient is φ = 19904717844.

The previous prime is 21010535503. The next prime is 21010535527. The reversal of 21010535521 is 12553501012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21010535521 - 2⁷ = 21010535393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010535527) 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, 552908811 + ... + 552908848.

It is an arithmetic number, because the mean of its divisors is an integer number (5529088300).

Almost surely, 2^21010535521 is an apocalyptic number.

It is an amenable number.

21010535521 is a deficient number, since it is larger than the sum of its proper divisors (1105817679).

21010535521 is a wasteful number, since it uses less digits than its factorization.

21010535521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1105817678.

The product of its (nonzero) digits is 1500, while the sum is 25.

The spelling of 21010535521 in words is "twenty-one billion, ten million, five hundred thirty-five thousand, five hundred twenty-one".