16699821 has 4 divisors (see below), whose sum is σ = 22266432. Its totient is φ = 11133212.

The previous prime is 16699777. The next prime is 16699843. The reversal of 16699821 is 12899661.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12899661 = 3 ⋅4299887.

It is a cyclic number.

It is not a de Polignac number, because 16699821 - 2¹⁰ = 16698797 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16699721) 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, 2783301 + ... + 2783306.

It is an arithmetic number, because the mean of its divisors is an integer number (5566608).

Almost surely, 2^16699821 is an apocalyptic number.

It is an amenable number.

16699821 is a deficient number, since it is larger than the sum of its proper divisors (5566611).

16699821 is an equidigital number, since it uses as much as digits as its factorization.

16699821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5566610.

The product of its digits is 46656, while the sum is 42.

The square root of 16699821 is about 4086.5414472387. The cubic root of 16699821 is about 255.6057417995.

The spelling of 16699821 in words is "sixteen million, six hundred ninety-nine thousand, eight hundred twenty-one".