216857825 has 12 divisors (see below), whose sum is σ = 270026988. Its totient is φ = 172761600.

The previous prime is 216857801. The next prime is 216857827. The reversal of 216857825 is 528758612.

It can be written as a sum of positive squares in 6 ways, for example, as 9728161 + 207129664 = 3119^2 + 14392^2 .

It is not a de Polignac number, because 216857825 - 2²⁰ = 215809249 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (216857827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11972 + ... + 24021.

It is an arithmetic number, because the mean of its divisors is an integer number (22502249).

Almost surely, 2^216857825 is an apocalyptic number.

216857825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

216857825 is a deficient number, since it is larger than the sum of its proper divisors (53169163).

216857825 is a wasteful number, since it uses less digits than its factorization.

216857825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36244 (or 36239 counting only the distinct ones).

The product of its digits is 268800, while the sum is 44.

The square root of 216857825 is about 14726.0933380174. The cubic root of 216857825 is about 600.7932332470.

The spelling of 216857825 in words is "two hundred sixteen million, eight hundred fifty-seven thousand, eight hundred twenty-five".