216123665 has 16 divisors (see below), whose sum is σ = 266215248. Its totient is φ = 168370176.

The previous prime is 216123653. The next prime is 216123673. The reversal of 216123665 is 566321612.

It can be written as a sum of positive squares in 8 ways, for example, as 14227984 + 201895681 = 3772^2 + 14209^2 .

It is a cyclic number.

It is not a de Polignac number, because 216123665 - 2⁸ = 216123409 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33329 + ... + 39281.

It is an arithmetic number, because the mean of its divisors is an integer number (16638453).

Almost surely, 2^216123665 is an apocalyptic number.

It is an amenable number.

216123665 is a deficient number, since it is larger than the sum of its proper divisors (50091583).

216123665 is a wasteful number, since it uses less digits than its factorization.

216123665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6148.

The product of its digits is 12960, while the sum is 32.

The square root of 216123665 is about 14701.1450234327. The cubic root of 216123665 is about 600.1144827844.

The spelling of 216123665 in words is "two hundred sixteen million, one hundred twenty-three thousand, six hundred sixty-five".