20533421521 has 4 divisors (see below), whose sum is σ = 20732775232. Its totient is φ = 20334067812.

The previous prime is 20533421501. The next prime is 20533421527. The reversal of 20533421521 is 12512433502.

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 20533421521 - 2¹⁹ = 20532897233 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20533421521.

It is not an unprimeable number, because it can be changed into a prime (20533421527) 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, 99676701 + ... + 99676906.

It is an arithmetic number, because the mean of its divisors is an integer number (5183193808).

Almost surely, 2^20533421521 is an apocalyptic number.

It is an amenable number.

20533421521 is a deficient number, since it is larger than the sum of its proper divisors (199353711).

20533421521 is a wasteful number, since it uses less digits than its factorization.

20533421521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199353710.

The product of its (nonzero) digits is 7200, while the sum is 28.

The spelling of 20533421521 in words is "twenty billion, five hundred thirty-three million, four hundred twenty-one thousand, five hundred twenty-one".