21244513 has 4 divisors (see below), whose sum is σ = 21362068. Its totient is φ = 21126960.

The previous prime is 21244507. The next prime is 21244583. The reversal of 21244513 is 31544212.

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 4695889 + 16548624 = 2167^2 + 4068^2 .

It is a cyclic number.

It is not a de Polignac number, because 21244513 - 2⁵ = 21244481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21244583) 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, 58506 + ... + 58867.

It is an arithmetic number, because the mean of its divisors is an integer number (5340517).

Almost surely, 2^21244513 is an apocalyptic number.

It is an amenable number.

21244513 is a deficient number, since it is larger than the sum of its proper divisors (117555).

21244513 is a wasteful number, since it uses less digits than its factorization.

21244513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117554.

The product of its digits is 960, while the sum is 22.

The square root of 21244513 is about 4609.1770415119. The cubic root of 21244513 is about 276.9590707033.

Adding to 21244513 its reverse (31544212), we get a palindrome (52788725).

The spelling of 21244513 in words is "twenty-one million, two hundred forty-four thousand, five hundred thirteen".