16990991 has 4 divisors (see below), whose sum is σ = 17016552. Its totient is φ = 16965432.

The previous prime is 16990913. The next prime is 16990993. The reversal of 16990991 is 19909961.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19909961 = 163 ⋅122147.

It is a cyclic number.

It is not a de Polignac number, because 16990991 - 2¹⁰ = 16989967 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 (16990993) 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, 11756 + ... + 13121.

It is an arithmetic number, because the mean of its divisors is an integer number (4254138).

Almost surely, 2^16990991 is an apocalyptic number.

16990991 is a deficient number, since it is larger than the sum of its proper divisors (25561).

16990991 is an equidigital number, since it uses as much as digits as its factorization.

16990991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25560.

The product of its (nonzero) digits is 39366, while the sum is 44.

The square root of 16990991 is about 4122.0129791159. The cubic root of 16990991 is about 257.0827301069.

The spelling of 16990991 in words is "sixteen million, nine hundred ninety thousand, nine hundred ninety-one".