16821949 has 4 divisors (see below), whose sum is σ = 16832700. Its totient is φ = 16811200.

The previous prime is 16821929. The next prime is 16821953. The reversal of 16821949 is 94912861.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 94912861 = 1861 ⋅51001.

It can be written as a sum of positive squares in 2 ways, for example, as 476100 + 16345849 = 690^2 + 4043^2 .

It is a cyclic number.

It is not a de Polignac number, because 16821949 - 2¹³ = 16813757 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16821929) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2524 + ... + 6325.

It is an arithmetic number, because the mean of its divisors is an integer number (4208175).

Almost surely, 2^16821949 is an apocalyptic number.

It is an amenable number.

16821949 is a deficient number, since it is larger than the sum of its proper divisors (10751).

16821949 is an equidigital number, since it uses as much as digits as its factorization.

16821949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10750.

The product of its digits is 31104, while the sum is 40.

The square root of 16821949 is about 4101.4569362606. The cubic root of 16821949 is about 256.2273218876.

The spelling of 16821949 in words is "sixteen million, eight hundred twenty-one thousand, nine hundred forty-nine".