216945 has 16 divisors (see below), whose sum is σ = 385920. Its totient is φ = 115632.

The previous prime is 216919. The next prime is 216947. The reversal of 216945 is 549612.

It is not a de Polignac number, because 216945 - 2¹⁰ = 215921 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between even and odd.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (216947) 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 15 ways as a sum of consecutive naturals, for example, 669 + ... + 938.

It is an arithmetic number, because the mean of its divisors is an integer number (24120).

2²¹⁶⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

216945 is a deficient number, since it is larger than the sum of its proper divisors (168975).

216945 is a wasteful number, since it uses less digits than its factorization.

216945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1621 (or 1615 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 216945 is about 465.7735501292. The cubic root of 216945 is about 60.0873727051.

The spelling of 216945 in words is "two hundred sixteen thousand, nine hundred forty-five".