1805681881 has 4 divisors (see below), whose sum is σ = 1854484132. Its totient is φ = 1756879632.

The previous prime is 1805681879. The next prime is 1805681887. The reversal of 1805681881 is 1881865081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1881865081 = 929 ⋅2025689.

It can be written as a sum of positive squares in 2 ways, for example, as 1074790656 + 730891225 = 32784^2 + 27035^2 .

It is a cyclic number.

It is not a de Polignac number, because 1805681881 - 2¹ = 1805681879 is a prime.

It is a super-2 number, since 2×1805681881² = 6520974110743396322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1805681887) 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, 24401070 + ... + 24401143.

It is an arithmetic number, because the mean of its divisors is an integer number (463621033).

Almost surely, 2^1805681881 is an apocalyptic number.

It is an amenable number.

1805681881 is a deficient number, since it is larger than the sum of its proper divisors (48802251).

1805681881 is an equidigital number, since it uses as much as digits as its factorization.

1805681881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48802250.

The product of its (nonzero) digits is 122880, while the sum is 46.

The square root of 1805681881 is about 42493.3157214167. The cubic root of 1805681881 is about 1217.7189935328.

The spelling of 1805681881 in words is "one billion, eight hundred five million, six hundred eighty-one thousand, eight hundred eighty-one".