16805881 has 4 divisors (see below), whose sum is σ = 17260132. Its totient is φ = 16351632.

The previous prime is 16805879. The next prime is 16805891. The reversal of 16805881 is 18850861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18850861 = 1307 ⋅14423.

It can be written as a sum of positive squares in 2 ways, for example, as 10949481 + 5856400 = 3309^2 + 2420^2 .

It is not a de Polignac number, because 16805881 - 2¹ = 16805879 is a prime.

It is a super-2 number, since 2×16805881² = 564875272372322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 454213 = 16805881 / (1 + 6 + 8 + 0 + 5 + 8 + 8 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16805881.

It is not an unprimeable number, because it can be changed into a prime (16805851) 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 3 ways as a sum of consecutive naturals, for example, 227070 + ... + 227143.

It is an arithmetic number, because the mean of its divisors is an integer number (4315033).

Almost surely, 2^16805881 is an apocalyptic number.

It is an amenable number.

16805881 is a deficient number, since it is larger than the sum of its proper divisors (454251).

16805881 is an equidigital number, since it uses as much as digits as its factorization.

16805881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454250.

The product of its (nonzero) digits is 15360, while the sum is 37.

The square root of 16805881 is about 4099.4976521520. The cubic root of 16805881 is about 256.1457147731.

The spelling of 16805881 in words is "sixteen million, eight hundred five thousand, eight hundred eighty-one".