21042881 has 8 divisors (see below), whose sum is σ = 21924000. Its totient is φ = 20179360.

The previous prime is 21042877. The next prime is 21042883. The reversal of 21042881 is 18824012.

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 21042881 - 2² = 21042877 is a prime.

It is a super-2 number, since 2×21042881² = 885605681560322, 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 21042881.

It is not an unprimeable number, because it can be changed into a prime (21042883) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1931 + ... + 6768.

It is an arithmetic number, because the mean of its divisors is an integer number (2740500).

Almost surely, 2^21042881 is an apocalyptic number.

It is an amenable number.

21042881 is a deficient number, since it is larger than the sum of its proper divisors (881119).

21042881 is an equidigital number, since it uses as much as digits as its factorization.

21042881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8799.

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 21042881 is about 4587.2520096459. The cubic root of 21042881 is about 276.0800763590.

Adding to 21042881 its reverse (18824012), we get a palindrome (39866893).

The spelling of 21042881 in words is "twenty-one million, forty-two thousand, eight hundred eighty-one".