21544122165 has 8 divisors (see below), whose sum is σ = 34470595488. Its totient is φ = 11490198480.

The previous prime is 21544122157. The next prime is 21544122169. The reversal of 21544122165 is 56122144512.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21544122165 - 2³ = 21544122157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21544122169) 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, 718137391 + ... + 718137420.

It is an arithmetic number, because the mean of its divisors is an integer number (4308824436).

Almost surely, 2^21544122165 is an apocalyptic number.

It is an amenable number.

21544122165 is a deficient number, since it is larger than the sum of its proper divisors (12926473323).

21544122165 is a wasteful number, since it uses less digits than its factorization.

21544122165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1436274819.

The product of its digits is 19200, while the sum is 33.

Adding to 21544122165 its reverse (56122144512), we get a palindrome (77666266677).

The spelling of 21544122165 in words is "twenty-one billion, five hundred forty-four million, one hundred twenty-two thousand, one hundred sixty-five".