216665815 has 8 divisors (see below), whose sum is σ = 268964640. Its totient is φ = 167355552.

The previous prime is 216665807. The next prime is 216665843. The reversal of 216665815 is 518566612.

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 216665815 - 2³ = 216665807 is a prime.

It is a super-2 number, since 2×216665815² = 93888150779228450, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 746979 + ... + 747268.

It is an arithmetic number, because the mean of its divisors is an integer number (33620580).

Almost surely, 2^216665815 is an apocalyptic number.

216665815 is a deficient number, since it is larger than the sum of its proper divisors (52298825).

216665815 is a wasteful number, since it uses less digits than its factorization.

216665815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1494281.

The product of its digits is 86400, while the sum is 40.

The square root of 216665815 is about 14719.5725141731. The cubic root of 216665815 is about 600.6158630087.

The spelling of 216665815 in words is "two hundred sixteen million, six hundred sixty-five thousand, eight hundred fifteen".