16693681 has 4 divisors (see below), whose sum is σ = 16702192. Its totient is φ = 16685172.

The previous prime is 16693679. The next prime is 16693709. The reversal of 16693681 is 18639661.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18639661 = 1409 ⋅13229.

It is a cyclic number.

It is not a de Polignac number, because 16693681 - 2¹ = 16693679 is a prime.

It is a super-2 number, since 2×16693681² = 557357970659522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16693631) 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, 346 + ... + 5788.

It is an arithmetic number, because the mean of its divisors is an integer number (4175548).

Almost surely, 2^16693681 is an apocalyptic number.

It is an amenable number.

16693681 is a deficient number, since it is larger than the sum of its proper divisors (8511).

16693681 is an equidigital number, since it uses as much as digits as its factorization.

16693681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8510.

The product of its digits is 46656, while the sum is 40.

The square root of 16693681 is about 4085.7901316636. The cubic root of 16693681 is about 255.5744118902.

The spelling of 16693681 in words is "sixteen million, six hundred ninety-three thousand, six hundred eighty-one".