21440043 has 18 divisors (see below), whose sum is σ = 32901804. Its totient is φ = 13450944.

The previous prime is 21440039. The next prime is 21440051. The reversal of 21440043 is 34004412.

It is not a de Polignac number, because 21440043 - 2² = 21440039 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21439998 and 21440025.

It is not an unprimeable number, because it can be changed into a prime (21440843) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1521 + ... + 6722.

It is an arithmetic number, because the mean of its divisors is an integer number (1827878).

Almost surely, 2^21440043 is an apocalyptic number.

21440043 is a deficient number, since it is larger than the sum of its proper divisors (11461761).

21440043 is a wasteful number, since it uses less digits than its factorization.

21440043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8283 (or 8263 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21440043 is about 4630.3394044065. The cubic root of 21440043 is about 277.8061680435.

Adding to 21440043 its reverse (34004412), we get a palindrome (55444455).

The spelling of 21440043 in words is "twenty-one million, four hundred forty thousand, forty-three".