21017043 has 8 divisors (see below), whose sum is σ = 31136400. Its totient is φ = 14011344.

The previous prime is 21017027. The next prime is 21017063. The reversal of 21017043 is 34071012.

It is not a de Polignac number, because 21017043 - 2⁴ = 21017027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21017063) 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 7 ways as a sum of consecutive naturals, for example, 389178 + ... + 389231.

It is an arithmetic number, because the mean of its divisors is an integer number (3892050).

Almost surely, 2^21017043 is an apocalyptic number.

21017043 is a deficient number, since it is larger than the sum of its proper divisors (10119357).

21017043 is an equidigital number, since it uses as much as digits as its factorization.

21017043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778418 (or 778412 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21017043 is about 4584.4348615724. The cubic root of 21017043 is about 275.9670329244.

Adding to 21017043 its reverse (34071012), we get a palindrome (55088055).

The spelling of 21017043 in words is "twenty-one million, seventeen thousand, forty-three".