21232513 has 2 divisors, whose sum is σ = 21232514. Its totient is φ = 21232512.

The previous prime is 21232511. The next prime is 21232531. The reversal of 21232513 is 31523212.

Together with next prime (21232531) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18249984 + 2982529 = 4272^2 + 1727^2 .

It is a cyclic number.

It is not a de Polignac number, because 21232513 - 2¹ = 21232511 is a prime.

Together with 21232511, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21232511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10616256 + 10616257.

It is an arithmetic number, because the mean of its divisors is an integer number (10616257).

Almost surely, 2^21232513 is an apocalyptic number.

It is an amenable number.

21232513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21232513 is an equidigital number, since it uses as much as digits as its factorization.

21232513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 360, while the sum is 19.

The square root of 21232513 is about 4607.8751068144. The cubic root of 21232513 is about 276.9069139447.

Adding to 21232513 its reverse (31523212), we get a palindrome (52755725).

The spelling of 21232513 in words is "twenty-one million, two hundred thirty-two thousand, five hundred thirteen".