16836821 has 4 divisors (see below), whose sum is σ = 16890252. Its totient is φ = 16783392.

The previous prime is 16836803. The next prime is 16836839. The reversal of 16836821 is 12863861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12863861 = 107 ⋅120223.

It is an interprime number because it is at equal distance from previous prime (16836803) and next prime (16836839).

It can be written as a sum of positive squares in 2 ways, for example, as 4056196 + 12780625 = 2014^2 + 3575^2 .

It is a cyclic number.

It is not a de Polignac number, because 16836821 - 2¹⁴ = 16820437 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 (16836871) 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, 26240 + ... + 26873.

It is an arithmetic number, because the mean of its divisors is an integer number (4222563).

Almost surely, 2^16836821 is an apocalyptic number.

It is an amenable number.

16836821 is a deficient number, since it is larger than the sum of its proper divisors (53431).

16836821 is an equidigital number, since it uses as much as digits as its factorization.

16836821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53430.

The product of its digits is 13824, while the sum is 35.

The square root of 16836821 is about 4103.2695500052. The cubic root of 16836821 is about 256.3028083907.

The spelling of 16836821 in words is "sixteen million, eight hundred thirty-six thousand, eight hundred twenty-one".