1009891 has 4 divisors (see below), whose sum is σ = 1025032. Its totient is φ = 994752.

The previous prime is 1009873. The next prime is 1009901. The reversal of 1009891 is 1989001.

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 1009891 - 2⁵ = 1009859 is a prime.

It is a Duffinian number.

1009891 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1009291) 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, 7470 + ... + 7603.

It is an arithmetic number, because the mean of its divisors is an integer number (256258).

2^1009891 is an apocalyptic number.

1009891 is a deficient number, since it is larger than the sum of its proper divisors (15141).

1009891 is an equidigital number, since it uses as much as digits as its factorization.

1009891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15140.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 1009891 is about 1004.9333311220. The cubic root of 1009891 is about 100.3286189132.

The spelling of 1009891 in words is "one million, nine thousand, eight hundred ninety-one".