16807991 has 4 divisors (see below), whose sum is σ = 17217984. Its totient is φ = 16398000.

The previous prime is 16807957. The next prime is 16807997. The reversal of 16807991 is 19970861.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 16807991 - 2¹⁰ = 16806967 is a prime.

It is a super-2 number, since 2×16807991² = 565017122912162, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (41), and also a Moran number because the ratio is a prime number: 409951 = 16807991 / (1 + 6 + 8 + 0 + 7 + 9 + 9 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16807997) 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, 204935 + ... + 205016.

It is an arithmetic number, because the mean of its divisors is an integer number (4304496).

Almost surely, 2^16807991 is an apocalyptic number.

16807991 is a deficient number, since it is larger than the sum of its proper divisors (409993).

16807991 is an equidigital number, since it uses as much as digits as its factorization.

16807991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 409992.

The product of its (nonzero) digits is 27216, while the sum is 41.

The square root of 16807991 is about 4099.7549926794. The cubic root of 16807991 is about 256.1564341327.

The spelling of 16807991 in words is "sixteen million, eight hundred seven thousand, nine hundred ninety-one".