21143881 has 8 divisors (see below), whose sum is σ = 23444928. Its totient is φ = 18906000.

The previous prime is 21143879. The next prime is 21143893. The reversal of 21143881 is 18834112.

21143881 is nontrivially palindromic in base 15.

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 21143881 - 2¹ = 21143879 is a prime.

It is a super-2 number, since 2×21143881² = 894127407484322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21143851) 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, 15085 + ... + 16426.

It is an arithmetic number, because the mean of its divisors is an integer number (2930616).

Almost surely, 2^21143881 is an apocalyptic number.

It is an amenable number.

21143881 is a deficient number, since it is larger than the sum of its proper divisors (2301047).

21143881 is a wasteful number, since it uses less digits than its factorization.

21143881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31583.

The product of its digits is 1536, while the sum is 28.

The square root of 21143881 is about 4598.2476009889. The cubic root of 21143881 is about 276.5210741851.

Adding to 21143881 its reverse (18834112), we get a palindrome (39977993).

It can be divided in two parts, 2114 and 3881, that added together give a palindrome (5995).

The spelling of 21143881 in words is "twenty-one million, one hundred forty-three thousand, eight hundred eighty-one".