21643521193 has 32 divisors (see below), whose sum is σ = 26661519360. Its totient is φ = 17171542080.

The previous prime is 21643521191. The next prime is 21643521199. The reversal of 21643521193 is 39112534612.

It is not a de Polignac number, because 21643521193 - 2¹ = 21643521191 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21643521191) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 657280 + ... + 689422.

It is an arithmetic number, because the mean of its divisors is an integer number (833172480).

Almost surely, 2^21643521193 is an apocalyptic number.

It is an amenable number.

21643521193 is a deficient number, since it is larger than the sum of its proper divisors (5017998167).

21643521193 is a wasteful number, since it uses less digits than its factorization.

21643521193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32317.

The product of its digits is 38880, while the sum is 37.

The spelling of 21643521193 in words is "twenty-one billion, six hundred forty-three million, five hundred twenty-one thousand, one hundred ninety-three".