21052122165 has 24 divisors (see below), whose sum is σ = 37667455488. Its totient is φ = 10865610720.

The previous prime is 21052122149. The next prime is 21052122167. The reversal of 21052122165 is 56122125012.

It is not a de Polignac number, because 21052122165 - 2⁴ = 21052122149 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21052122167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7544169 + ... + 7546958.

It is an arithmetic number, because the mean of its divisors is an integer number (1569477312).

Almost surely, 2^21052122165 is an apocalyptic number.

It is an amenable number.

21052122165 is a deficient number, since it is larger than the sum of its proper divisors (16615333323).

21052122165 is a wasteful number, since it uses less digits than its factorization.

21052122165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15091169 (or 15091166 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

Adding to 21052122165 its reverse (56122125012), we get a palindrome (77174247177).

The spelling of 21052122165 in words is "twenty-one billion, fifty-two million, one hundred twenty-two thousand, one hundred sixty-five".