215993 has 4 divisors (see below), whose sum is σ = 225408. Its totient is φ = 206580.

The previous prime is 215983. The next prime is 216023. The reversal of 215993 is 399512.

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 a cyclic number.

It is not a de Polignac number, because 215993 - 2⁸ = 215737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4673 + ... + 4718.

It is an arithmetic number, because the mean of its divisors is an integer number (56352).

215993 is a Friedman number, since it can be written as (51+9)^3-9+2, using all its digits and the basic arithmetic operations.

2²¹⁵⁹⁹³ is an apocalyptic number.

215993 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

215993 is a deficient number, since it is larger than the sum of its proper divisors (9415).

215993 is an equidigital number, since it uses as much as digits as its factorization.

215993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9414.

The product of its digits is 2430, while the sum is 29.

The square root of 215993 is about 464.7504706829. The cubic root of 215993 is about 59.9993518449. Note that the first 3 decimals are identical.

The spelling of 215993 in words is "two hundred fifteen thousand, nine hundred ninety-three".