206870991 has 16 divisors (see below), whose sum is σ = 279628800. Its totient is φ = 136025568.

The previous prime is 206870981. The next prime is 206871073. The reversal of 206870991 is 199078602.

It is not a de Polignac number, because 206870991 - 2¹⁴ = 206854607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206870921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 76830 + ... + 79476.

It is an arithmetic number, because the mean of its divisors is an integer number (17476800).

Almost surely, 2^206870991 is an apocalyptic number.

206870991 is a deficient number, since it is larger than the sum of its proper divisors (72757809).

206870991 is a wasteful number, since it uses less digits than its factorization.

206870991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2998.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 206870991 is about 14383.0104985013. The cubic root of 206870991 is about 591.4252538713.

The spelling of 206870991 in words is "two hundred six million, eight hundred seventy thousand, nine hundred ninety-one".