20506165 has 8 divisors (see below), whose sum is σ = 26055000. Its totient is φ = 15439872.

The previous prime is 20506163. The next prime is 20506181. The reversal of 20506165 is 56160502.

It can be written as a sum of positive squares in 4 ways, for example, as 4490161 + 16016004 = 2119^2 + 4002^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20506165 - 2¹ = 20506163 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20506163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 120540 + ... + 120709.

It is an arithmetic number, because the mean of its divisors is an integer number (3256875).

Almost surely, 2^20506165 is an apocalyptic number.

It is an amenable number.

20506165 is a deficient number, since it is larger than the sum of its proper divisors (5548835).

20506165 is a wasteful number, since it uses less digits than its factorization.

20506165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241271.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 20506165 is about 4528.3733282493. The cubic root of 20506165 is about 273.7126162610.

Adding to 20506165 its reverse (56160502), we get a palindrome (76666667).

The spelling of 20506165 in words is "twenty million, five hundred six thousand, one hundred sixty-five".