216621252 has 18 divisors (see below), whose sum is σ = 547570478. Its totient is φ = 72207072.

The previous prime is 216621247. The next prime is 216621253. The reversal of 216621252 is 252126612.

216621252 is a `hidden beast` number, since 2 + 16 + 621 + 25 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 195608196 + 21013056 = 13986^2 + 4584^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is not an unprimeable number, because it can be changed into a prime (216621253) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3008593 + ... + 3008664.

Almost surely, 2^216621252 is an apocalyptic number.

It is an amenable number.

216621252 is an abundant number, since it is smaller than the sum of its proper divisors (330949226).

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

216621252 is a wasteful number, since it uses less digits than its factorization.

216621252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6017267 (or 6017262 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 216621252 is about 14718.0587035111. The cubic root of 216621252 is about 600.5746827239.

Adding to 216621252 its reverse (252126612), we get a palindrome (468747864).

The spelling of 216621252 in words is "two hundred sixteen million, six hundred twenty-one thousand, two hundred fifty-two".