216855551 has 8 divisors (see below), whose sum is σ = 237057408. Its totient is φ = 196735000.

The previous prime is 216855539. The next prime is 216855559. The reversal of 216855551 is 155558612.

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

It is not a de Polignac number, because 216855551 - 2²⁶ = 149746687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216855559) 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, 14675 + ... + 25476.

It is an arithmetic number, because the mean of its divisors is an integer number (29632176).

Almost surely, 2^216855551 is an apocalyptic number.

216855551 is a deficient number, since it is larger than the sum of its proper divisors (20201857).

216855551 is a wasteful number, since it uses less digits than its factorization.

216855551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40653.

The product of its digits is 60000, while the sum is 38.

The square root of 216855551 is about 14726.0161279282. The cubic root of 216855551 is about 600.7911332404.

The spelling of 216855551 in words is "two hundred sixteen million, eight hundred fifty-five thousand, five hundred fifty-one".