216420305 has 8 divisors (see below), whose sum is σ = 260341800. Its totient is φ = 172711296.

The previous prime is 216420257. The next prime is 216420307. The reversal of 216420305 is 503024612.

It can be written as a sum of positive squares in 4 ways, for example, as 17497489 + 198922816 = 4183^2 + 14104^2 .

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 216420305 - 2¹² = 216416209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216420307) 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, 50870 + ... + 54959.

It is an arithmetic number, because the mean of its divisors is an integer number (32542725).

Almost surely, 2^216420305 is an apocalyptic number.

It is an amenable number.

216420305 is a deficient number, since it is larger than the sum of its proper divisors (43921495).

216420305 is a wasteful number, since it uses less digits than its factorization.

216420305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106243.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 216420305 is about 14711.2305739527. The cubic root of 216420305 is about 600.3889191450.

Adding to 216420305 its reverse (503024612), we get a palindrome (719444917).

The spelling of 216420305 in words is "two hundred sixteen million, four hundred twenty thousand, three hundred five".