21543523165 has 8 divisors (see below), whose sum is σ = 25987580928. Its totient is φ = 17144583120.

The previous prime is 21543523163. The next prime is 21543523187. The reversal of 21543523165 is 56132534512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21543523165 - 2¹ = 21543523163 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21543523163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11278377 + ... + 11280286.

It is an arithmetic number, because the mean of its divisors is an integer number (3248447616).

Almost surely, 2^21543523165 is an apocalyptic number.

It is an amenable number.

21543523165 is a deficient number, since it is larger than the sum of its proper divisors (4444057763).

21543523165 is a wasteful number, since it uses less digits than its factorization.

21543523165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22558859.

The product of its digits is 108000, while the sum is 37.

The spelling of 21543523165 in words is "twenty-one billion, five hundred forty-three million, five hundred twenty-three thousand, one hundred sixty-five".