21007043 has 4 divisors (see below), whose sum is σ = 21018168. Its totient is φ = 20995920.

The previous prime is 21007013. The next prime is 21007067. The reversal of 21007043 is 34070012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21007043 - 2¹⁰ = 21006019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21007013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1946 + ... + 6767.

It is an arithmetic number, because the mean of its divisors is an integer number (5254542).

Almost surely, 2^21007043 is an apocalyptic number.

21007043 is a deficient number, since it is larger than the sum of its proper divisors (11125).

21007043 is an equidigital number, since it uses as much as digits as its factorization.

21007043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11124.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 21007043 is about 4583.3440848359. The cubic root of 21007043 is about 275.9232572113.

Adding to 21007043 its reverse (34070012), we get a palindrome (55077055).

The spelling of 21007043 in words is "twenty-one million, seven thousand, forty-three".