216561616 has 10 divisors (see below), whose sum is σ = 419588162. Its totient is φ = 108280800.

The previous prime is 216561607. The next prime is 216561619. The reversal of 216561616 is 616165612.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 135489600 + 81072016 = 11640^2 + 9004^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216561619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6767535 + ... + 6767566.

Almost surely, 2^216561616 is an apocalyptic number.

It is an amenable number.

216561616 is a deficient number, since it is larger than the sum of its proper divisors (203026546).

216561616 is a wasteful number, since it uses less digits than its factorization.

216561616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13535109 (or 13535103 counting only the distinct ones).

The product of its digits is 12960, while the sum is 34.

The square root of 216561616 is about 14716.0326175230. The cubic root of 216561616 is about 600.5195647724.

The spelling of 216561616 in words is "two hundred sixteen million, five hundred sixty-one thousand, six hundred sixteen".