216521234 has 4 divisors (see below), whose sum is σ = 324781854. Its totient is φ = 108260616.

The previous prime is 216521233. The next prime is 216521251. The reversal of 216521234 is 432125612.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 139169209 + 77352025 = 11797^2 + 8795^2 .

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

It is not an unprimeable number, because it can be changed into a prime (216521233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 54130307 + ... + 54130310.

Almost surely, 2^216521234 is an apocalyptic number.

216521234 is a deficient number, since it is larger than the sum of its proper divisors (108260620).

216521234 is a wasteful number, since it uses less digits than its factorization.

216521234 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108260619.

The product of its digits is 2880, while the sum is 26.

The square root of 216521234 is about 14714.6605125637. The cubic root of 216521234 is about 600.4822363837.

Adding to 216521234 its reverse (432125612), we get a palindrome (648646846).

The spelling of 216521234 in words is "two hundred sixteen million, five hundred twenty-one thousand, two hundred thirty-four".