205212120165 has 80 divisors (see below), whose sum is σ = 396561673200. Its totient is φ = 100924766208.

The previous prime is 205212120163. The next prime is 205212120193. The reversal of 205212120165 is 561021212502.

205212120165 is a `hidden beast` number, since 2 + 0 + 521 + 2 + 120 + 16 + 5 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 80178452964 + 125033667201 = 283158^2 + 353601^2 .

It is not a de Polignac number, because 205212120165 - 2¹ = 205212120163 is a prime.

It is a super-2 number, since 2×205212120165² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205212120163) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 5293071 + ... + 5331699.

It is an arithmetic number, because the mean of its divisors is an integer number (4957020915).

Almost surely, 2^205212120165 is an apocalyptic number.

It is an amenable number.

205212120165 is a deficient number, since it is larger than the sum of its proper divisors (191349553035).

205212120165 is a wasteful number, since it uses less digits than its factorization.

205212120165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39668 (or 39659 counting only the distinct ones).

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

Adding to 205212120165 its reverse (561021212502), we get a palindrome (766233332667).

The spelling of 205212120165 in words is "two hundred five billion, two hundred twelve million, one hundred twenty thousand, one hundred sixty-five".