216621312 has 36 divisors (see below), whose sum is σ = 576530640. Its totient is φ = 72206848.

The previous prime is 216621311. The next prime is 216621367. The reversal of 216621312 is 213126612.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (216621311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 140262 + ... + 141797.

It is an arithmetic number, because the mean of its divisors is an integer number (16014740).

Almost surely, 2^216621312 is an apocalyptic number.

It is an amenable number.

216621312 is an abundant number, since it is smaller than the sum of its proper divisors (359909328).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

216621312 is an equidigital number, since it uses as much as digits as its factorization.

216621312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282078 (or 282064 counting only the distinct ones).

The product of its digits is 864, while the sum is 24.

The square root of 216621312 is about 14718.0607418233. The cubic root of 216621312 is about 600.5747381732.

Adding to 216621312 its reverse (213126612), we get a palindrome (429747924).

The spelling of 216621312 in words is "two hundred sixteen million, six hundred twenty-one thousand, three hundred twelve".