16365991 has 4 divisors (see below), whose sum is σ = 16425352. Its totient is φ = 16306632.

The previous prime is 16365977. The next prime is 16366001. The reversal of 16365991 is 19956361.

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 16365991 - 2¹⁵ = 16333223 is a prime.

It is a super-2 number, since 2×16365991² = 535691322824162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16365911) 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, 29265 + ... + 29818.

It is an arithmetic number, because the mean of its divisors is an integer number (4106338).

Almost surely, 2^16365991 is an apocalyptic number.

16365991 is a deficient number, since it is larger than the sum of its proper divisors (59361).

16365991 is an equidigital number, since it uses as much as digits as its factorization.

16365991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59360.

The product of its digits is 43740, while the sum is 40.

The square root of 16365991 is about 4045.4902051544. The cubic root of 16365991 is about 253.8910759118.

The spelling of 16365991 in words is "sixteen million, three hundred sixty-five thousand, nine hundred ninety-one".