21068881 has 4 divisors (see below), whose sum is σ = 21305700. Its totient is φ = 20832064.

The previous prime is 21068869. The next prime is 21068893. The reversal of 21068881 is 18886012.

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 (21068869) and next prime (21068893).

It can be written as a sum of positive squares in 2 ways, for example, as 3294225 + 17774656 = 1815^2 + 4216^2 .

It is a cyclic number.

It is not a de Polignac number, because 21068881 - 2¹¹ = 21066833 is a prime.

It is a super-2 number, since 2×21068881² = 887795493184322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21063881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 118276 + ... + 118453.

It is an arithmetic number, because the mean of its divisors is an integer number (5326425).

Almost surely, 2^21068881 is an apocalyptic number.

It is an amenable number.

21068881 is a deficient number, since it is larger than the sum of its proper divisors (236819).

21068881 is an equidigital number, since it uses as much as digits as its factorization.

21068881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236818.

The product of its (nonzero) digits is 6144, while the sum is 34.

The square root of 21068881 is about 4590.0850754643. The cubic root of 21068881 is about 276.1937351884.

The spelling of 21068881 in words is "twenty-one million, sixty-eight thousand, eight hundred eighty-one".