206909981 has 8 divisors (see below), whose sum is σ = 217932000. Its totient is φ = 195901200.

The previous prime is 206909971. The next prime is 206909993. The reversal of 206909981 is 189909602.

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 206909981 - 2⁶ = 206909917 is a prime.

It is a super-2 number, since 2×206909981² = 85623480474840722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206909971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61031 + ... + 64331.

It is an arithmetic number, because the mean of its divisors is an integer number (27241500).

Almost surely, 2^206909981 is an apocalyptic number.

It is an amenable number.

206909981 is a deficient number, since it is larger than the sum of its proper divisors (11022019).

206909981 is a wasteful number, since it uses less digits than its factorization.

206909981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6619.

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 206909981 is about 14384.3658532450. The cubic root of 206909981 is about 591.4624078192.

The spelling of 206909981 in words is "two hundred six million, nine hundred nine thousand, nine hundred eighty-one".