21665111154 has 16 divisors (see below), whose sum is σ = 43332307392. Its totient is φ = 7221356208.

The previous prime is 21665111147. The next prime is 21665111159. The reversal of 21665111154 is 45111156612.

It is not an unprimeable number, because it can be changed into a prime (21665111159) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69987 + ... + 219609.

It is an arithmetic number, because the mean of its divisors is an integer number (2708269212).

Almost surely, 2^21665111154 is an apocalyptic number.

21665111154 is an abundant number, since it is smaller than the sum of its proper divisors (21667196238).

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

21665111154 is a wasteful number, since it uses less digits than its factorization.

21665111154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173761.

The product of its digits is 7200, while the sum is 33.

Adding to 21665111154 its reverse (45111156612), we get a palindrome (66776267766).

The spelling of 21665111154 in words is "twenty-one billion, six hundred sixty-five million, one hundred eleven thousand, one hundred fifty-four".