21611135137541 has 4 divisors (see below), whose sum is σ = 21617116634412. Its totient is φ = 21605153640672.

The previous prime is 21611135137517. The next prime is 21611135137619. The reversal of 21611135137541 is 14573153111612.

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 3246739100641 + 18364396036900 = 1801871^2 + 4285370^2 .

It is a cyclic number.

It is not a de Polignac number, because 21611135137541 - 2²⁶ = 21611068028677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21611135137841) 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, 2990743016 + ... + 2990750241.

It is an arithmetic number, because the mean of its divisors is an integer number (5404279158603).

Almost surely, 2^{21611135137541} is an apocalyptic number.

It is an amenable number.

21611135137541 is a deficient number, since it is larger than the sum of its proper divisors (5981496871).

21611135137541 is an equidigital number, since it uses as much as digits as its factorization.

21611135137541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5981496870.

The product of its digits is 75600, while the sum is 41.

The spelling of 21611135137541 in words is "twenty-one trillion, six hundred eleven billion, one hundred thirty-five million, one hundred thirty-seven thousand, five hundred forty-one".