216631 has 4 divisors (see below), whose sum is σ = 229392. Its totient is φ = 203872.

The previous prime is 216617. The next prime is 216641. The reversal of 216631 is 136612.

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 216631 - 2⁹ = 216119 is a prime.

It is a super-2 number, since 2×216631² = 93857980322, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 216599 and 216608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216641) 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, 6355 + ... + 6388.

It is an arithmetic number, because the mean of its divisors is an integer number (57348).

2²¹⁶⁶³¹ is an apocalyptic number.

216631 is a deficient number, since it is larger than the sum of its proper divisors (12761).

216631 is a wasteful number, since it uses less digits than its factorization.

216631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12760.

The product of its digits is 216, while the sum is 19.

The square root of 216631 is about 465.4363544030. The cubic root of 216631 is about 60.0583691249.

Subtracting from 216631 its sum of digits (19), we obtain a palindrome (216612).

It can be divided in two parts, 2166 and 31, that added together give a cube (2197 = 13³).

The spelling of 216631 in words is "two hundred sixteen thousand, six hundred thirty-one".