21665111160 has 128 divisors (see below), whose sum is σ = 81033177600. Its totient is φ = 4501839360.

The previous prime is 21665111159. The next prime is 21665111173. The reversal of 21665111160 is 6111156612.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1163115 + ... + 1181594.

It is an arithmetic number, because the mean of its divisors is an integer number (633071700).

Almost surely, 2^21665111160 is an apocalyptic number.

21665111160 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21665111160 is an abundant number, since it is smaller than the sum of its proper divisors (59368066440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21665111160 is a wasteful number, since it uses less digits than its factorization.

21665111160 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2344741 (or 2344737 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 30.

Adding to 21665111160 its reverse (6111156612), we get a palindrome (27776267772).

The spelling of 21665111160 in words is "twenty-one billion, six hundred sixty-five million, one hundred eleven thousand, one hundred sixty".