21213443 has 6 divisors (see below), whose sum is σ = 22389084. Its totient is φ = 20096604.

The previous prime is 21213431. The next prime is 21213449. The reversal of 21213443 is 34431212.

It is not a de Polignac number, because 21213443 - 2⁴ = 21213427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21213449) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 29021 + ... + 29742.

It is an arithmetic number, because the mean of its divisors is an integer number (3731514).

Almost surely, 2^21213443 is an apocalyptic number.

21213443 is a deficient number, since it is larger than the sum of its proper divisors (1175641).

21213443 is an equidigital number, since it uses as much as digits as its factorization.

21213443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58801 (or 58782 counting only the distinct ones).

The product of its digits is 576, while the sum is 20.

The square root of 21213443 is about 4605.8053584580. The cubic root of 21213443 is about 276.8239877178.

Adding to 21213443 its reverse (34431212), we get a palindrome (55644655).

The spelling of 21213443 in words is "twenty-one million, two hundred thirteen thousand, four hundred forty-three".