205121025999 has 32 divisors (see below), whose sum is σ = 304430427840. Its totient is φ = 136501272576.

The previous prime is 205121025953. The next prime is 205121026051. The reversal of 205121025999 is 999520121502.

205121025999 is a `hidden beast` number, since 2 + 0 + 51 + 2 + 1 + 0 + 2 + 599 + 9 = 666.

It is not a de Polignac number, because 205121025999 - 2⁸ = 205121025743 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205121025929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42615717 + ... + 42620529.

It is an arithmetic number, because the mean of its divisors is an integer number (9513450870).

Almost surely, 2^205121025999 is an apocalyptic number.

205121025999 is a deficient number, since it is larger than the sum of its proper divisors (99309401841).

205121025999 is a wasteful number, since it uses less digits than its factorization.

205121025999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7336 (or 7330 counting only the distinct ones).

The product of its (nonzero) digits is 145800, while the sum is 45.

The spelling of 205121025999 in words is "two hundred five billion, one hundred twenty-one million, twenty-five thousand, nine hundred ninety-nine".