215121065 has 4 divisors (see below), whose sum is σ = 258145284. Its totient is φ = 172096848.

The previous prime is 215121031. The next prime is 215121083. The reversal of 215121065 is 560121512.

It is a happy number.

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 23658496 + 191462569 = 4864^2 + 13837^2 .

It is a cyclic number.

It is not a de Polignac number, because 215121065 - 2¹⁰ = 215120041 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 215121065.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21512102 + ... + 21512111.

It is an arithmetic number, because the mean of its divisors is an integer number (64536321).

Almost surely, 2^215121065 is an apocalyptic number.

It is an amenable number.

215121065 is a deficient number, since it is larger than the sum of its proper divisors (43024219).

215121065 is an equidigital number, since it uses as much as digits as its factorization.

215121065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43024218.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 215121065 is about 14667.0059998624. The cubic root of 215121065 is about 599.1850649321.

Adding to 215121065 its reverse (560121512), we get a palindrome (775242577).

The spelling of 215121065 in words is "two hundred fifteen million, one hundred twenty-one thousand, sixty-five".