216843781 has 16 divisors (see below), whose sum is σ = 270839808. Its totient is φ = 168663600.

The previous prime is 216843769. The next prime is 216843787. The reversal of 216843781 is 187348612.

It is not a de Polignac number, because 216843781 - 2⁵ = 216843749 is a prime.

It is a super-2 number, since 2×216843781² = 94042450716751922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216843787) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 46356 + ... + 50818.

It is an arithmetic number, because the mean of its divisors is an integer number (16927488).

Almost surely, 2^216843781 is an apocalyptic number.

It is an amenable number.

216843781 is a deficient number, since it is larger than the sum of its proper divisors (53996027).

216843781 is a wasteful number, since it uses less digits than its factorization.

216843781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5112.

The product of its digits is 64512, while the sum is 40.

The square root of 216843781 is about 14725.6164896414. The cubic root of 216843781 is about 600.7802635784.

The spelling of 216843781 in words is "two hundred sixteen million, eight hundred forty-three thousand, seven hundred eighty-one".