13215809 has 2 divisors, whose sum is σ = 13215810. Its totient is φ = 13215808.

The previous prime is 13215803. The next prime is 13215821. The reversal of 13215809 is 90851231.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7139584 + 6076225 = 2672^2 + 2465^2 .

It is an emirp because it is prime and its reverse (90851231) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13215809 - 2¹² = 13211713 is a prime.

It is not a weakly prime, because it can be changed into another prime (13215803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6607904 + 6607905.

It is an arithmetic number, because the mean of its divisors is an integer number (6607905).

Almost surely, 2^13215809 is an apocalyptic number.

It is an amenable number.

13215809 is a deficient number, since it is larger than the sum of its proper divisors (1).

13215809 is an equidigital number, since it uses as much as digits as its factorization.

13215809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 13215809 is about 3635.3554159119. The cubic root of 13215809 is about 236.4274607049.

The spelling of 13215809 in words is "thirteen million, two hundred fifteen thousand, eight hundred nine".