16999991 has 4 divisors (see below), whose sum is σ = 17019072. Its totient is φ = 16980912.

The previous prime is 16999963. The next prime is 16999999. The reversal of 16999991 is 19999961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19999961 = 547 ⋅36563.

It is a cyclic number.

It is not a de Polignac number, because 16999991 - 2¹⁴ = 16983607 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 (16999999) 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, 8135 + ... + 10008.

It is an arithmetic number, because the mean of its divisors is an integer number (4254768).

Almost surely, 2^16999991 is an apocalyptic number.

16999991 is a deficient number, since it is larger than the sum of its proper divisors (19081).

16999991 is an equidigital number, since it uses as much as digits as its factorization.

16999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19080.

The product of its digits is 354294, while the sum is 53.

The square root of 16999991 is about 4123.1045342072. The cubic root of 16999991 is about 257.1281136903.

The spelling of 16999991 in words is "sixteen million, nine hundred ninety-nine thousand, nine hundred ninety-one".