216521211 has 8 divisors (see below), whose sum is σ = 295408960. Its totient is φ = 140990472.

The previous prime is 216521203. The next prime is 216521219. The reversal of 216521211 is 112125612.

It is an interprime number because it is at equal distance from previous prime (216521203) and next prime (216521219).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 216521211 - 2³ = 216521203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216521219) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 839101 + ... + 839358.

It is an arithmetic number, because the mean of its divisors is an integer number (36926120).

Almost surely, 2^216521211 is an apocalyptic number.

216521211 is a deficient number, since it is larger than the sum of its proper divisors (78887749).

216521211 is a wasteful number, since it uses less digits than its factorization.

216521211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1678505.

The product of its digits is 240, while the sum is 21.

The square root of 216521211 is about 14714.6597310301. The cubic root of 216521211 is about 600.4822151216.

Adding to 216521211 its reverse (112125612), we get a palindrome (328646823).

The spelling of 216521211 in words is "two hundred sixteen million, five hundred twenty-one thousand, two hundred eleven".