206653557991 has 4 divisors (see below), whose sum is σ = 207735513984. Its totient is φ = 205571602000.

The previous prime is 206653557967. The next prime is 206653557997. The reversal of 206653557991 is 199755356602.

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

It is a cyclic number.

It is not a de Polignac number, because 206653557991 - 2¹⁹ = 206653033703 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 (206653557997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 540977710 + ... + 540978091.

It is an arithmetic number, because the mean of its divisors is an integer number (51933878496).

Almost surely, 2^206653557991 is an apocalyptic number.

206653557991 is a deficient number, since it is larger than the sum of its proper divisors (1081955993).

206653557991 is a wasteful number, since it uses less digits than its factorization.

206653557991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1081955992.

The product of its (nonzero) digits is 15309000, while the sum is 58.

The spelling of 206653557991 in words is "two hundred six billion, six hundred fifty-three million, five hundred fifty-seven thousand, nine hundred ninety-one".