216521204 has 6 divisors (see below), whose sum is σ = 378912114. Its totient is φ = 108260600.

The previous prime is 216521203. The next prime is 216521219. The reversal of 216521204 is 402125612.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 216031204 + 490000 = 14698^2 + 700^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 216521204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216521203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27065147 + ... + 27065154.

It is an arithmetic number, because the mean of its divisors is an integer number (63152019).

Almost surely, 2^216521204 is an apocalyptic number.

It is an amenable number.

216521204 is a deficient number, since it is larger than the sum of its proper divisors (162390910).

216521204 is a wasteful number, since it uses less digits than its factorization.

216521204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54130305 (or 54130303 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 216521204 is about 14714.6594931721. The cubic root of 216521204 is about 600.4822086505.

Adding to 216521204 its reverse (402125612), we get a palindrome (618646816).

The spelling of 216521204 in words is "two hundred sixteen million, five hundred twenty-one thousand, two hundred four".