21655666505716 has 12 divisors (see below), whose sum is σ = 37913253182532. Its totient is φ = 10823308453568.

The previous prime is 21655666505713. The next prime is 21655666505717. The reversal of 21655666505716 is 61750566655612.

It can be written as a sum of positive squares in 2 ways, for example, as 11654918044900 + 10000748460816 = 3413930^2 + 3162396^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21655666505713) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1131189055 + ... + 1131208198.

It is an arithmetic number, because the mean of its divisors is an integer number (3159437765211).

Almost surely, 2^{21655666505716} is an apocalyptic number.

It is an amenable number.

21655666505716 is a deficient number, since it is larger than the sum of its proper divisors (16257586676816).

21655666505716 is a wasteful number, since it uses less digits than its factorization.

21655666505716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2262399650 (or 2262399648 counting only the distinct ones).

The product of its (nonzero) digits is 68040000, while the sum is 61.

The spelling of 21655666505716 in words is "twenty-one trillion, six hundred fifty-five billion, six hundred sixty-six million, five hundred five thousand, seven hundred sixteen".