16556993 has 4 divisors (see below), whose sum is σ = 16837680. Its totient is φ = 16276308.

The previous prime is 16556983. The next prime is 16557001. The reversal of 16556993 is 39965561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16556993 - 2⁴ = 16556977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16556933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 140255 + ... + 140372.

It is an arithmetic number, because the mean of its divisors is an integer number (4209420).

Almost surely, 2^16556993 is an apocalyptic number.

It is an amenable number.

16556993 is a deficient number, since it is larger than the sum of its proper divisors (280687).

16556993 is an equidigital number, since it uses as much as digits as its factorization.

16556993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280686.

The product of its digits is 218700, while the sum is 44.

The square root of 16556993 is about 4069.0285081331. The cubic root of 16556993 is about 254.8749508621.

The spelling of 16556993 in words is "sixteen million, five hundred fifty-six thousand, nine hundred ninety-three".