206439687991 has 8 divisors (see below), whose sum is σ = 209775515264. Its totient is φ = 203111350200.

The previous prime is 206439687983. The next prime is 206439688027. The reversal of 206439687991 is 199786934602.

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 206439687991 - 2³ = 206439687983 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 (206439687491) 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 7 ways as a sum of consecutive naturals, for example, 1816785 + ... + 1927066.

It is an arithmetic number, because the mean of its divisors is an integer number (26221939408).

Almost surely, 2^206439687991 is an apocalyptic number.

206439687991 is a deficient number, since it is larger than the sum of its proper divisors (3335827273).

206439687991 is an equidigital number, since it uses as much as digits as its factorization.

206439687991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3744741.

The product of its (nonzero) digits is 35271936, while the sum is 64.

The spelling of 206439687991 in words is "two hundred six billion, four hundred thirty-nine million, six hundred eighty-seven thousand, nine hundred ninety-one".