16443681 has 4 divisors (see below), whose sum is σ = 21924912. Its totient is φ = 10962452.

The previous prime is 16443677. The next prime is 16443703. The reversal of 16443681 is 18634461.

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.

It is a cyclic number.

It is not a de Polignac number, because 16443681 - 2² = 16443677 is a prime.

It is a super-3 number, since 3×16443681³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (16443611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2740611 + ... + 2740616.

It is an arithmetic number, because the mean of its divisors is an integer number (5481228).

Almost surely, 2^16443681 is an apocalyptic number.

It is an amenable number.

16443681 is a deficient number, since it is larger than the sum of its proper divisors (5481231).

16443681 is an equidigital number, since it uses as much as digits as its factorization.

16443681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5481230.

The product of its digits is 13824, while the sum is 33.

The square root of 16443681 is about 4055.0808869861. The cubic root of 16443681 is about 254.2921855111.

The spelling of 16443681 in words is "sixteen million, four hundred forty-three thousand, six hundred eighty-one".