21352013 has 4 divisors (see below), whose sum is σ = 21702108. Its totient is φ = 21001920.

The previous prime is 21352007. The next prime is 21352031. The reversal of 21352013 is 31025312.

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 4721929 + 16630084 = 2173^2 + 4078^2 .

It is a cyclic number.

It is not a de Polignac number, because 21352013 - 2²⁴ = 4574797 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21351982 and 21352000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21352213) 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 in 3 ways as a sum of consecutive naturals, for example, 174956 + ... + 175077.

It is an arithmetic number, because the mean of its divisors is an integer number (5425527).

Almost surely, 2^21352013 is an apocalyptic number.

It is an amenable number.

21352013 is a deficient number, since it is larger than the sum of its proper divisors (350095).

21352013 is an equidigital number, since it uses as much as digits as its factorization.

21352013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350094.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21352013 is about 4620.8238442944. The cubic root of 21352013 is about 277.4254346096.

Adding to 21352013 its reverse (31025312), we get a palindrome (52377325).

The spelling of 21352013 in words is "twenty-one million, three hundred fifty-two thousand, thirteen".