216851669 has 4 divisors (see below), whose sum is σ = 217050444. Its totient is φ = 216652896.

The previous prime is 216851639. The next prime is 216851681. The reversal of 216851669 is 966158612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 35545444 + 181306225 = 5962^2 + 13465^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216851669 is a prime.

It is a super-2 number, since 2×216851669² = 94049292696171122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216851629) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97742 + ... + 99935.

It is an arithmetic number, because the mean of its divisors is an integer number (54262611).

Almost surely, 2^216851669 is an apocalyptic number.

It is an amenable number.

216851669 is a deficient number, since it is larger than the sum of its proper divisors (198775).

216851669 is a wasteful number, since it uses less digits than its factorization.

216851669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198774.

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

The square root of 216851669 is about 14725.8843197955. The cubic root of 216851669 is about 600.7875482348.

The spelling of 216851669 in words is "two hundred sixteen million, eight hundred fifty-one thousand, six hundred sixty-nine".