21162021165 has 24 divisors (see below), whose sum is σ = 36686003328. Its totient is φ = 11284821600.

The previous prime is 21162021163. The next prime is 21162021187. The reversal of 21162021165 is 56112026112.

21162021165 is a `hidden beast` number, since 2 + 1 + 1 + 620 + 21 + 16 + 5 = 666.

It is not a de Polignac number, because 21162021165 - 2¹ = 21162021163 is a prime.

It is a super-2 number, since 2×21162021165² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21162021163) 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, 334840 + ... + 392990.

It is an arithmetic number, because the mean of its divisors is an integer number (1528583472).

Almost surely, 2^21162021165 is an apocalyptic number.

It is an amenable number.

21162021165 is a deficient number, since it is larger than the sum of its proper divisors (15523982163).

21162021165 is a wasteful number, since it uses less digits than its factorization.

21162021165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66249 (or 66246 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

Adding to 21162021165 its reverse (56112026112), we get a palindrome (77274047277).

The spelling of 21162021165 in words is "twenty-one billion, one hundred sixty-two million, twenty-one thousand, one hundred sixty-five".