861800891 has 8 divisors (see below), whose sum is σ = 985780224. Its totient is φ = 738037800.

The previous prime is 861800881. The next prime is 861800903. The reversal of 861800891 is 198008168.

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 861800891 - 2⁶ = 861800827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (861800861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45425 + ... + 61538.

It is an arithmetic number, because the mean of its divisors is an integer number (123222528).

Almost surely, 2^861800891 is an apocalyptic number.

861800891 is a deficient number, since it is larger than the sum of its proper divisors (123979333).

861800891 is a wasteful number, since it uses less digits than its factorization.

861800891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108121.

The product of its (nonzero) digits is 27648, while the sum is 41.

The square root of 861800891 is about 29356.4454762493. The cubic root of 861800891 is about 951.6318733422.

The spelling of 861800891 in words is "eight hundred sixty-one million, eight hundred thousand, eight hundred ninety-one".