16990681 has 4 divisors (see below), whose sum is σ = 17195472. Its totient is φ = 16785892.

The previous prime is 16990679. The next prime is 16990691. The reversal of 16990681 is 18609961.

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: 18609961 = 2593 ⋅7177.

It is a cyclic number.

It is not a de Polignac number, because 16990681 - 2¹ = 16990679 is a prime.

It is a super-2 number, since 2×16990681² = 577366481687522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16990601) 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, 102271 + ... + 102436.

It is an arithmetic number, because the mean of its divisors is an integer number (4298868).

Almost surely, 2^16990681 is an apocalyptic number.

It is an amenable number.

16990681 is a deficient number, since it is larger than the sum of its proper divisors (204791).

16990681 is an equidigital number, since it uses as much as digits as its factorization.

16990681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204790.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 16990681 is about 4121.9753759575. The cubic root of 16990681 is about 257.0811666091.

It can be divided in two parts, 16990 and 681, that added together give a palindrome (17671).

The spelling of 16990681 in words is "sixteen million, nine hundred ninety thousand, six hundred eighty-one".