16331891 has 4 divisors (see below), whose sum is σ = 16414992. Its totient is φ = 16248792.

The previous prime is 16331879. The next prime is 16331921. The reversal of 16331891 is 19813361.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19813361 = 53 ⋅373837.

It is a cyclic number.

It is not a de Polignac number, because 16331891 - 2¹⁸ = 16069747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16331831) 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, 41255 + ... + 41648.

It is an arithmetic number, because the mean of its divisors is an integer number (4103748).

Almost surely, 2^16331891 is an apocalyptic number.

16331891 is a deficient number, since it is larger than the sum of its proper divisors (83101).

16331891 is an equidigital number, since it uses as much as digits as its factorization.

16331891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83100.

The product of its digits is 3888, while the sum is 32.

The square root of 16331891 is about 4041.2734379153. The cubic root of 16331891 is about 253.7146184096.

The spelling of 16331891 in words is "sixteen million, three hundred thirty-one thousand, eight hundred ninety-one".