16555999 has 2 divisors, whose sum is σ = 16556000. Its totient is φ = 16555998.

The previous prime is 16555997. The next prime is 16556009. The reversal of 16555999 is 99955561.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 16555999 - 2¹ = 16555997 is a prime.

It is a super-2 number, since 2×16555999² = 548202205776002, which contains 22 as substring.

Together with 16555997, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16555997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8277999 + 8278000.

It is an arithmetic number, because the mean of its divisors is an integer number (8278000).

Almost surely, 2^16555999 is an apocalyptic number.

16555999 is a deficient number, since it is larger than the sum of its proper divisors (1).

16555999 is an equidigital number, since it uses as much as digits as its factorization.

16555999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 546750, while the sum is 49.

The square root of 16555999 is about 4068.9063641229. The cubic root of 16555999 is about 254.8698502828.

The spelling of 16555999 in words is "sixteen million, five hundred fifty-five thousand, nine hundred ninety-nine".