215791 has 4 divisors (see below), whose sum is σ = 222784. Its totient is φ = 208800.

The previous prime is 215771. The next prime is 215797. The reversal of 215791 is 197512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 215791 - 2⁹ = 215279 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215797) 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, 3450 + ... + 3511.

It is an arithmetic number, because the mean of its divisors is an integer number (55696).

2²¹⁵⁷⁹¹ is an apocalyptic number.

215791 is a deficient number, since it is larger than the sum of its proper divisors (6993).

215791 is an equidigital number, since it uses as much as digits as its factorization.

215791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6992.

The product of its digits is 630, while the sum is 25.

The square root of 215791 is about 464.5330989284. The cubic root of 215791 is about 59.9806419032.

The spelling of 215791 in words is "two hundred fifteen thousand, seven hundred ninety-one".