16993991 has 4 divisors (see below), whose sum is σ = 19421712. Its totient is φ = 14566272.

The previous prime is 16993969. The next prime is 16994009. The reversal of 16993991 is 19939961.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 16993991 - 2¹⁰ = 16992967 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 (16933991) 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, 1213850 + ... + 1213863.

It is an arithmetic number, because the mean of its divisors is an integer number (4855428).

Almost surely, 2^16993991 is an apocalyptic number.

16993991 is a deficient number, since it is larger than the sum of its proper divisors (2427721).

16993991 is an equidigital number, since it uses as much as digits as its factorization.

16993991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2427720.

The product of its digits is 118098, while the sum is 47.

The square root of 16993991 is about 4122.3768629275. The cubic root of 16993991 is about 257.0978597484.

The spelling of 16993991 in words is "sixteen million, nine hundred ninety-three thousand, nine hundred ninety-one".