15991099 has 4 divisors (see below), whose sum is σ = 15999480. Its totient is φ = 15982720.

The previous prime is 15991097. The next prime is 15991109. The reversal of 15991099 is 99019951.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 99019951 = 17 ⋅5824703.

It is a cyclic number.

It is not a de Polignac number, because 15991099 - 2¹ = 15991097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15991097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 219 + ... + 5659.

It is an arithmetic number, because the mean of its divisors is an integer number (3999870).

Almost surely, 2^15991099 is an apocalyptic number.

15991099 is a deficient number, since it is larger than the sum of its proper divisors (8381).

15991099 is an equidigital number, since it uses as much as digits as its factorization.

15991099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8380.

The product of its (nonzero) digits is 32805, while the sum is 43.

The square root of 15991099 is about 3998.8872202151. The cubic root of 15991099 is about 251.9374739894.

The spelling of 15991099 in words is "fifteen million, nine hundred ninety-one thousand, ninety-nine".