205861891 has 8 divisors (see below), whose sum is σ = 227448864. Its totient is φ = 185328000.

The previous prime is 205861889. The next prime is 205861897. The reversal of 205861891 is 198168502.

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 205861891 - 2¹ = 205861889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205861897) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 262860 + ... + 263641.

It is an arithmetic number, because the mean of its divisors is an integer number (28431108).

Almost surely, 2^205861891 is an apocalyptic number.

205861891 is a deficient number, since it is larger than the sum of its proper divisors (21586973).

205861891 is a wasteful number, since it uses less digits than its factorization.

205861891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526541.

The product of its (nonzero) digits is 34560, while the sum is 40.

The square root of 205861891 is about 14347.8880327385. Note that the first 3 decimals coincide. The cubic root of 205861891 is about 590.4620444630.

The spelling of 205861891 in words is "two hundred five million, eight hundred sixty-one thousand, eight hundred ninety-one".