216616661 has 8 divisors (see below), whose sum is σ = 219024384. Its totient is φ = 214220160.

The previous prime is 216616649. The next prime is 216616667. The reversal of 216616661 is 166616612.

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

It is a cyclic number.

It is not a de Polignac number, because 216616661 - 2¹⁴ = 216600277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216616667) 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, 39461 + ... + 44613.

It is an arithmetic number, because the mean of its divisors is an integer number (27378048).

Almost surely, 2^216616661 is an apocalyptic number.

It is an amenable number.

216616661 is a deficient number, since it is larger than the sum of its proper divisors (2407723).

216616661 is a wasteful number, since it uses less digits than its factorization.

216616661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5611.

The product of its digits is 15552, while the sum is 35.

The square root of 216616661 is about 14717.9027378224. The cubic root of 216616661 is about 600.5704398994.

The spelling of 216616661 in words is "two hundred sixteen million, six hundred sixteen thousand, six hundred sixty-one".