206405987 has 4 divisors (see below), whose sum is σ = 217269480. Its totient is φ = 195542496.

The previous prime is 206405951. The next prime is 206405989. The reversal of 206405987 is 789504602.

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 206405987 - 2¹⁰ = 206404963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (206405989) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5431718 + ... + 5431755.

It is an arithmetic number, because the mean of its divisors is an integer number (54317370).

Almost surely, 2^206405987 is an apocalyptic number.

206405987 is a deficient number, since it is larger than the sum of its proper divisors (10863493).

206405987 is a wasteful number, since it uses less digits than its factorization.

206405987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10863492.

The product of its (nonzero) digits is 120960, while the sum is 41.

The square root of 206405987 is about 14366.8363601734. The cubic root of 206405987 is about 590.9817867866.

The spelling of 206405987 in words is "two hundred six million, four hundred five thousand, nine hundred eighty-seven".