215121 has 4 divisors (see below), whose sum is σ = 286832. Its totient is φ = 143412.

The previous prime is 215087. The next prime is 215123. The reversal of 215121 is 121512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 215121 - 2⁷ = 214993 is a prime.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 215097 and 215106.

It is not an unprimeable number, because it can be changed into a prime (215123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35851 + ... + 35856.

It is an arithmetic number, because the mean of its divisors is an integer number (71708).

2²¹⁵¹²¹ is an apocalyptic number.

It is an amenable number.

215121 is a deficient number, since it is larger than the sum of its proper divisors (71711).

215121 is an equidigital number, since it uses as much as digits as its factorization.

215121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71710.

The product of its digits is 20, while the sum is 12.

The square root of 215121 is about 463.8113840776. The cubic root of 215121 is about 59.9185004583.

Adding to 215121 its reverse (121512), we get a palindrome (336633).

The spelling of 215121 in words is "two hundred fifteen thousand, one hundred twenty-one".