205121131 has 4 divisors (see below), whose sum is σ = 215917000. Its totient is φ = 194325264.

The previous prime is 205121117. The next prime is 205121143. The reversal of 205121131 is 131121502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 131121502 = 2 ⋅65560751.

It is a cyclic number.

It is not a de Polignac number, because 205121131 - 2⁷ = 205121003 is a prime.

It is a super-2 number, since 2×205121131² = 84149356765438322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205121431) 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, 5397906 + ... + 5397943.

It is an arithmetic number, because the mean of its divisors is an integer number (53979250).

Almost surely, 2^205121131 is an apocalyptic number.

205121131 is a deficient number, since it is larger than the sum of its proper divisors (10795869).

205121131 is a wasteful number, since it uses less digits than its factorization.

205121131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10795868.

The product of its (nonzero) digits is 60, while the sum is 16.

The square root of 205121131 is about 14322.0505165985. The cubic root of 205121131 is about 589.7529665804.

Adding to 205121131 its reverse (131121502), we get a palindrome (336242633).

The spelling of 205121131 in words is "two hundred five million, one hundred twenty-one thousand, one hundred thirty-one".