21611173645361 has 4 divisors (see below), whose sum is σ = 21611202916452. Its totient is φ = 21611144374272.

The previous prime is 21611173645331. The next prime is 21611173645381. The reversal of 21611173645361 is 16354637111612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18916897614736 + 2694276030625 = 4349356^2 + 1641425^2 .

It is a cyclic number.

It is not a de Polignac number, because 21611173645361 - 2⁶ = 21611173645297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21611173645331) 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, 13498640 + ... + 15014513.

It is an arithmetic number, because the mean of its divisors is an integer number (5402800729113).

Almost surely, 2^{21611173645361} is an apocalyptic number.

It is an amenable number.

21611173645361 is a deficient number, since it is larger than the sum of its proper divisors (29271091).

21611173645361 is an equidigital number, since it uses as much as digits as its factorization.

21611173645361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29271090.

The product of its digits is 544320, while the sum is 47.

The spelling of 21611173645361 in words is "twenty-one trillion, six hundred eleven billion, one hundred seventy-three million, six hundred forty-five thousand, three hundred sixty-one".