21541844864 has 16 divisors (see below), whose sum is σ = 42915394320. Its totient is φ = 10770922368.

The previous prime is 21541844843. The next prime is 21541844867. The reversal of 21541844864 is 46844814512.

It is a tau number, because it is divible by the number of its divisors (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21541844867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84147704 + ... + 84147959.

It is an arithmetic number, because the mean of its divisors is an integer number (2682212145).

Almost surely, 2^21541844864 is an apocalyptic number.

It is an amenable number.

21541844864 is a deficient number, since it is larger than the sum of its proper divisors (21373549456).

21541844864 is an equidigital number, since it uses as much as digits as its factorization.

21541844864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168295677 (or 168295665 counting only the distinct ones).

The product of its digits is 983040, while the sum is 47.

The spelling of 21541844864 in words is "twenty-one billion, five hundred forty-one million, eight hundred forty-four thousand, eight hundred sixty-four".