206123805621 has 20 divisors (see below), whose sum is σ = 308047667532. Its totient is φ = 137355922368.

The previous prime is 206123805617. The next prime is 206123805709. The reversal of 206123805621 is 126508321602.

206123805621 is a `hidden beast` number, since 2 + 0 + 6 + 1 + 23 + 8 + 0 + 5 + 621 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 61389972900 + 144733832721 = 247770^2 + 380439^2 .

It is not a de Polignac number, because 206123805621 - 2² = 206123805617 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206123845621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 367870 + ... + 739983.

Almost surely, 2^206123805621 is an apocalyptic number.

It is an amenable number.

206123805621 is a deficient number, since it is larger than the sum of its proper divisors (101923861911).

206123805621 is a wasteful number, since it uses less digits than its factorization.

206123805621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1110162 (or 1110153 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 206123805621 in words is "two hundred six billion, one hundred twenty-three million, eight hundred five thousand, six hundred twenty-one".