21447313 has 4 divisors (see below), whose sum is σ = 21536548. Its totient is φ = 21358080.

The previous prime is 21447311. The next prime is 21447337. The reversal of 21447313 is 31374412.

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 18861649 + 2585664 = 4343^2 + 1608^2 .

It is a cyclic number.

It is not a de Polignac number, because 21447313 - 2¹ = 21447311 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21447311) 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, 44256 + ... + 44737.

It is an arithmetic number, because the mean of its divisors is an integer number (5384137).

Almost surely, 2^21447313 is an apocalyptic number.

It is an amenable number.

21447313 is a deficient number, since it is larger than the sum of its proper divisors (89235).

21447313 is an equidigital number, since it uses as much as digits as its factorization.

21447313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89234.

The product of its digits is 2016, while the sum is 25.

The square root of 21447313 is about 4631.1243775135. The cubic root of 21447313 is about 277.8375644762.

The spelling of 21447313 in words is "twenty-one million, four hundred forty-seven thousand, three hundred thirteen".