15916991 has 4 divisors (see below), whose sum is σ = 15925800. Its totient is φ = 15908184.

The previous prime is 15916963. The next prime is 15917017. The reversal of 15916991 is 19961951.

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.

It is a cyclic number.

It is not a de Polignac number, because 15916991 - 2¹⁰ = 15915967 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 (15916931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 596 + ... + 5673.

It is an arithmetic number, because the mean of its divisors is an integer number (3981450).

Almost surely, 2^15916991 is an apocalyptic number.

15916991 is a deficient number, since it is larger than the sum of its proper divisors (8809).

15916991 is an equidigital number, since it uses as much as digits as its factorization.

15916991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8808.

The product of its digits is 21870, while the sum is 41.

The square root of 15916991 is about 3989.6103819797. The cubic root of 15916991 is about 251.5476842553.

The spelling of 15916991 in words is "fifteen million, nine hundred sixteen thousand, nine hundred ninety-one".