1231891 has 8 divisors (see below), whose sum is σ = 1289520. Its totient is φ = 1175328.

The previous prime is 1231889. The next prime is 1231943. The reversal of 1231891 is 1981321.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1231891 - 2¹ = 1231889 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 (1231831) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2905 + ... + 3301.

It is an arithmetic number, because the mean of its divisors is an integer number (161190).

2^1231891 is an apocalyptic number.

1231891 is a deficient number, since it is larger than the sum of its proper divisors (57629).

1231891 is a wasteful number, since it uses less digits than its factorization.

1231891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533.

The product of its digits is 432, while the sum is 25.

The square root of 1231891 is about 1109.9058518631. The cubic root of 1231891 is about 107.1990065903.

The spelling of 1231891 in words is "one million, two hundred thirty-one thousand, eight hundred ninety-one".