205121555221 has 8 divisors (see below), whose sum is σ = 223787974464. Its totient is φ = 186458303520.

The previous prime is 205121555207. The next prime is 205121555231. The reversal of 205121555221 is 122555121502.

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 205121555221 - 2⁵ = 205121555189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205121555231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 655456 + ... + 916441.

It is an arithmetic number, because the mean of its divisors is an integer number (27973496808).

Almost surely, 2^205121555221 is an apocalyptic number.

It is an amenable number.

205121555221 is a deficient number, since it is larger than the sum of its proper divisors (18666419243).

205121555221 is a wasteful number, since it uses less digits than its factorization.

205121555221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1583771.

The product of its (nonzero) digits is 10000, while the sum is 31.

Adding to 205121555221 its reverse (122555121502), we get a palindrome (327676676723).

The spelling of 205121555221 in words is "two hundred five billion, one hundred twenty-one million, five hundred fifty-five thousand, two hundred twenty-one".