216859661 has 8 divisors (see below), whose sum is σ = 222257280. Its totient is φ = 211528512.

The previous prime is 216859649. The next prime is 216859679. The reversal of 216859661 is 166958612.

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 216859661 - 2¹⁸ = 216597517 is a prime.

It is a super-2 number, since 2×216859661² = 94056225138069842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216859691) 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, 9980 + ... + 23093.

It is an arithmetic number, because the mean of its divisors is an integer number (27782160).

Almost surely, 2^216859661 is an apocalyptic number.

It is an amenable number.

216859661 is a deficient number, since it is larger than the sum of its proper divisors (5397619).

216859661 is an equidigital number, since it uses as much as digits as its factorization.

216859661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33235.

The product of its digits is 155520, while the sum is 44.

The square root of 216859661 is about 14726.1556762110. The cubic root of 216859661 is about 600.7949287561.

The spelling of 216859661 in words is "two hundred sixteen million, eight hundred fifty-nine thousand, six hundred sixty-one".