216606431 has 4 divisors (see below), whose sum is σ = 216636264. Its totient is φ = 216576600.

The previous prime is 216606407. The next prime is 216606443. The reversal of 216606431 is 134606612.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 216606431 - 2¹⁸ = 216344287 is a prime.

It is a super-2 number, since 2×216606431² = 93836691901115522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 216606394 and 216606403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216606461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3821 + ... + 21161.

It is an arithmetic number, because the mean of its divisors is an integer number (54159066).

Almost surely, 2^216606431 is an apocalyptic number.

216606431 is a deficient number, since it is larger than the sum of its proper divisors (29833).

216606431 is a wasteful number, since it uses less digits than its factorization.

216606431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29832.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 216606431 is about 14717.5551977902. Note that the first 3 decimals coincide. The cubic root of 216606431 is about 600.5609855138.

The spelling of 216606431 in words is "two hundred sixteen million, six hundred six thousand, four hundred thirty-one".