205161500161 has 4 divisors (see below), whose sum is σ = 206977088772. Its totient is φ = 203345911552.

The previous prime is 205161500119. The next prime is 205161500183. The reversal of 205161500161 is 161005161502.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 27145857600 + 178015642561 = 164760^2 + 421919^2 .

It is a cyclic number.

It is not a de Polignac number, because 205161500161 - 2⁹ = 205161499649 is a prime.

It is a super-2 number, since 2×205161500161² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205161500191) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 907794136 + ... + 907794361.

It is an arithmetic number, because the mean of its divisors is an integer number (51744272193).

Almost surely, 2^205161500161 is an apocalyptic number.

It is an amenable number.

205161500161 is a deficient number, since it is larger than the sum of its proper divisors (1815588611).

205161500161 is a wasteful number, since it uses less digits than its factorization.

205161500161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1815588610.

The product of its (nonzero) digits is 1800, while the sum is 28.

Adding to 205161500161 its reverse (161005161502), we get a palindrome (366166661663).

The spelling of 205161500161 in words is "two hundred five billion, one hundred sixty-one million, five hundred thousand, one hundred sixty-one".