21473321 has 4 divisors (see below), whose sum is σ = 21878532. Its totient is φ = 21068112.

The previous prime is 21473293. The next prime is 21473351. The reversal of 21473321 is 12337412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8970025 + 12503296 = 2995^2 + 3536^2 .

It is a cyclic number.

It is not a de Polignac number, because 21473321 - 2¹⁴ = 21456937 is a prime.

It is a super-2 number, since 2×21473321² = 922207029538082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21473351) 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 3 ways as a sum of consecutive naturals, for example, 202526 + ... + 202631.

It is an arithmetic number, because the mean of its divisors is an integer number (5469633).

Almost surely, 2^21473321 is an apocalyptic number.

It is an amenable number.

21473321 is a deficient number, since it is larger than the sum of its proper divisors (405211).

21473321 is an equidigital number, since it uses as much as digits as its factorization.

21473321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405210.

The product of its digits is 1008, while the sum is 23.

The square root of 21473321 is about 4633.9314841719. The cubic root of 21473321 is about 277.9498253219.

The spelling of 21473321 in words is "twenty-one million, four hundred seventy-three thousand, three hundred twenty-one".