20855881 has 4 divisors (see below), whose sum is σ = 21141652. Its totient is φ = 20570112.

The previous prime is 20855869. The next prime is 20855893. The reversal of 20855881 is 18855802.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (20855869) and next prime (20855893).

It can be written as a sum of positive squares in 2 ways, for example, as 4372281 + 16483600 = 2091^2 + 4060^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20855881 is a prime.

It is a super-2 number, since 2×20855881² = 869935544572322, which contains 22 as substring.

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 20855881.

It is not an unprimeable number, because it can be changed into a prime (20855831) 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, 142776 + ... + 142921.

It is an arithmetic number, because the mean of its divisors is an integer number (5285413).

Almost surely, 2^20855881 is an apocalyptic number.

It is an amenable number.

20855881 is a deficient number, since it is larger than the sum of its proper divisors (285771).

20855881 is an equidigital number, since it uses as much as digits as its factorization.

20855881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285770.

The product of its (nonzero) digits is 25600, while the sum is 37.

The square root of 20855881 is about 4566.8239510627. The cubic root of 20855881 is about 275.2598359573.

It can be divided in two parts, 20855 and 881, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 20855881 in words is "twenty million, eight hundred fifty-five thousand, eight hundred eighty-one".