1609891 has 4 divisors (see below), whose sum is σ = 1644192. Its totient is φ = 1575592.

The previous prime is 1609879. The next prime is 1609897. The reversal of 1609891 is 1989061.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1989061 = 89 ⋅22349.

It is a cyclic number.

It is not a de Polignac number, because 1609891 - 2⁷ = 1609763 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 (1609897) 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, 17080 + ... + 17173.

It is an arithmetic number, because the mean of its divisors is an integer number (411048).

2^1609891 is an apocalyptic number.

1609891 is a deficient number, since it is larger than the sum of its proper divisors (34301).

1609891 is an equidigital number, since it uses as much as digits as its factorization.

1609891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34300.

The product of its (nonzero) digits is 3888, while the sum is 34.

The square root of 1609891 is about 1268.8148013008. The cubic root of 1609891 is about 117.2012267535.

It can be divided in two parts, 1609 and 891, that added together give a square (2500 = 50²).

The spelling of 1609891 in words is "one million, six hundred nine thousand, eight hundred ninety-one".