216281705 has 4 divisors (see below), whose sum is σ = 259538052. Its totient is φ = 173025360.

The previous prime is 216281677. The next prime is 216281729. The reversal of 216281705 is 507182612.

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 57320041 + 158961664 = 7571^2 + 12608^2 .

It is not a de Polignac number, because 216281705 - 2⁶ = 216281641 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21628166 + ... + 21628175.

It is an arithmetic number, because the mean of its divisors is an integer number (64884513).

Almost surely, 2^216281705 is an apocalyptic number.

It is an amenable number.

216281705 is a deficient number, since it is larger than the sum of its proper divisors (43256347).

216281705 is an equidigital number, since it uses as much as digits as its factorization.

216281705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43256346.

The product of its (nonzero) digits is 6720, while the sum is 32.

The square root of 216281705 is about 14706.5191326840. The cubic root of 216281705 is about 600.2607246510.

The spelling of 216281705 in words is "two hundred sixteen million, two hundred eighty-one thousand, seven hundred five".