206388891 has 48 divisors (see below), whose sum is σ = 334623744. Its totient is φ = 126624384.

The previous prime is 206388883. The next prime is 206388893. The reversal of 206388891 is 198883602.

206388891 is a `hidden beast` number, since 2 + 0 + 638 + 8 + 8 + 9 + 1 = 666.

It is not a de Polignac number, because 206388891 - 2³ = 206388883 is a prime.

It is not an unprimeable number, because it can be changed into a prime (206388893) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 193626 + ... + 194688.

It is an arithmetic number, because the mean of its divisors is an integer number (6971328).

Almost surely, 2^206388891 is an apocalyptic number.

206388891 is a deficient number, since it is larger than the sum of its proper divisors (128234853).

206388891 is a wasteful number, since it uses less digits than its factorization.

206388891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1142 (or 1130 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The square root of 206388891 is about 14366.2413664814. The cubic root of 206388891 is about 590.9654699092.

The spelling of 206388891 in words is "two hundred six million, three hundred eighty-eight thousand, eight hundred ninety-one".