21313205 has 8 divisors (see below), whose sum is σ = 25604952. Its totient is φ = 17031168.

The previous prime is 21313199. The next prime is 21313207. The reversal of 21313205 is 50231312.

It can be written as a sum of positive squares in 4 ways, for example, as 1162084 + 20151121 = 1078^2 + 4489^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21313205 - 2¹⁶ = 21247669 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21313207) 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 7 ways as a sum of consecutive naturals, for example, 3917 + ... + 7613.

It is an arithmetic number, because the mean of its divisors is an integer number (3200619).

Almost surely, 2^21313205 is an apocalyptic number.

It is an amenable number.

21313205 is a deficient number, since it is larger than the sum of its proper divisors (4291747).

21313205 is a wasteful number, since it uses less digits than its factorization.

21313205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4855.

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

The square root of 21313205 is about 4616.6226833043. The cubic root of 21313205 is about 277.2572559999.

Adding to 21313205 its reverse (50231312), we get a palindrome (71544517).

The spelling of 21313205 in words is "twenty-one million, three hundred thirteen thousand, two hundred five".