216399555 has 24 divisors (see below), whose sum is σ = 377966160. Its totient is φ = 114528960.

The previous prime is 216399529. The next prime is 216399559. The reversal of 216399555 is 555993612.

216399555 is a `hidden beast` number, since 2 + 1 + 6 + 3 + 99 + 555 = 666.

It is not a de Polignac number, because 216399555 - 2⁵ = 216399523 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 216399555.

It is not an unprimeable number, because it can be changed into a prime (216399559) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12460 + ... + 24249.

It is an arithmetic number, because the mean of its divisors is an integer number (15748590).

Almost surely, 2^216399555 is an apocalyptic number.

216399555 is a deficient number, since it is larger than the sum of its proper divisors (161566605).

216399555 is a wasteful number, since it uses less digits than its factorization.

216399555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36851 (or 36848 counting only the distinct ones).

The product of its digits is 364500, while the sum is 45.

The square root of 216399555 is about 14710.5253135298. The cubic root of 216399555 is about 600.3697304522.

The spelling of 216399555 in words is "two hundred sixteen million, three hundred ninety-nine thousand, five hundred fifty-five".