16016821 has 4 divisors (see below), whose sum is σ = 16026444. Its totient is φ = 16007200.

The previous prime is 16016813. The next prime is 16016837. The reversal of 16016821 is 12861061.

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: 12861061 = 17 ⋅756533.

It can be written as a sum of positive squares in 2 ways, for example, as 14668900 + 1347921 = 3830^2 + 1161^2 .

It is a cyclic number.

It is not a de Polignac number, because 16016821 - 2³ = 16016813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16016321) 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, 1600 + ... + 5881.

It is an arithmetic number, because the mean of its divisors is an integer number (4006611).

Almost surely, 2^16016821 is an apocalyptic number.

It is an amenable number.

16016821 is a deficient number, since it is larger than the sum of its proper divisors (9623).

16016821 is an equidigital number, since it uses as much as digits as its factorization.

16016821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9622.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 16016821 is about 4002.1020726613. The cubic root of 16016821 is about 252.0724837683.

Adding to 16016821 its reverse (12861061), we get a palindrome (28877882).

The spelling of 16016821 in words is "sixteen million, sixteen thousand, eight hundred twenty-one".