216521123 has 32 divisors (see below), whose sum is σ = 275692032. Its totient is φ = 165484800.

The previous prime is 216521119. The next prime is 216521159. The reversal of 216521123 is 321125612.

It is not a de Polignac number, because 216521123 - 2² = 216521119 is a prime.

It is a super-2 number, since 2×216521123² = 93762793410362258, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (216521113) 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 31 ways as a sum of consecutive naturals, for example, 488540 + ... + 488982.

It is an arithmetic number, because the mean of its divisors is an integer number (8615376).

Almost surely, 2^216521123 is an apocalyptic number.

216521123 is a deficient number, since it is larger than the sum of its proper divisors (59170909).

216521123 is a wasteful number, since it uses less digits than its factorization.

216521123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 635.

The product of its digits is 720, while the sum is 23.

The square root of 216521123 is about 14714.6567408146. The cubic root of 216521123 is about 600.4821337709.

Adding to 216521123 its reverse (321125612), we get a palindrome (537646735).

The spelling of 216521123 in words is "two hundred sixteen million, five hundred twenty-one thousand, one hundred twenty-three".