16778 has 4 divisors (see below), whose sum is σ = 25170. Its totient is φ = 8388.

The previous prime is 16763. The next prime is 16787. The reversal of 16778 is 87761.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 11449 + 5329 = 107^2 + 73^2 .

It is a plaindrome in base 10.

It is a nialpdrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 16778.

It is an unprimeable number.

16778 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4193 + ... + 4196.

2¹⁶⁷⁷⁸ is an apocalyptic number.

16778 is a deficient number, since it is larger than the sum of its proper divisors (8392).

16778 is an equidigital number, since it uses as much as digits as its factorization.

16778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8391.

The product of its digits is 2352, while the sum is 29.

The square root of 16778 is about 129.5299193237. The cubic root of 16778 is about 25.6003987568.

Adding to 16778 its sum of digits (29), we get a 5-th power (16807 = 7⁵).

The spelling of 16778 in words is "sixteen thousand, seven hundred seventy-eight".