216681406 has 8 divisors (see below), whose sum is σ = 325090584. Its totient is φ = 108317880.

The previous prime is 216681391. The next prime is 216681407. The reversal of 216681406 is 604186612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×216681406² = 93901663412273672, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216681407) 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, 5421 + ... + 21511.

It is an arithmetic number, because the mean of its divisors is an integer number (40636323).

Almost surely, 2^216681406 is an apocalyptic number.

216681406 is a deficient number, since it is larger than the sum of its proper divisors (108409178).

216681406 is a wasteful number, since it uses less digits than its factorization.

216681406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22826.

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 216681406 is about 14720.1021056241. The cubic root of 216681406 is about 600.6302691843.

The spelling of 216681406 in words is "two hundred sixteen million, six hundred eighty-one thousand, four hundred six".