215321 has 4 divisors (see below), whose sum is σ = 216612. Its totient is φ = 214032.

The previous prime is 215317. The next prime is 215329. The reversal of 215321 is 123512.

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 211600 + 3721 = 460^2 + 61^2 .

It is a cyclic number.

It is not a de Polignac number, because 215321 - 2² = 215317 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 215296 and 215305.

It is not an unprimeable number, because it can be changed into a prime (215329) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 350 + ... + 743.

It is an arithmetic number, because the mean of its divisors is an integer number (54153).

2²¹⁵³²¹ is an apocalyptic number.

It is an amenable number.

215321 is a deficient number, since it is larger than the sum of its proper divisors (1291).

215321 is a wasteful number, since it uses less digits than its factorization.

215321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1290.

The product of its digits is 60, while the sum is 14.

The square root of 215321 is about 464.0269388732. The cubic root of 215321 is about 59.9370636363.

Adding to 215321 its reverse (123512), we get a palindrome (338833).

Subtracting from 215321 its reverse (123512), we obtain a square (91809 = 303²).

The spelling of 215321 in words is "two hundred fifteen thousand, three hundred twenty-one".