1239991 has 4 divisors (see below), whose sum is σ = 1268872. Its totient is φ = 1211112.

The previous prime is 1239989. The next prime is 1240007. The reversal of 1239991 is 1999321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1999321 = 23 ⋅86927.

It is a cyclic number.

It is not a de Polignac number, because 1239991 - 2¹ = 1239989 is a prime.

It is a Duffinian number.

1239991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1239911) 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, 14376 + ... + 14461.

It is an arithmetic number, because the mean of its divisors is an integer number (317218).

2^1239991 is an apocalyptic number.

1239991 is a deficient number, since it is larger than the sum of its proper divisors (28881).

1239991 is an equidigital number, since it uses as much as digits as its factorization.

1239991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28880.

The product of its digits is 4374, while the sum is 34.

The square root of 1239991 is about 1113.5488314394. The cubic root of 1239991 is about 107.4334471780.

The spelling of 1239991 in words is "one million, two hundred thirty-nine thousand, nine hundred ninety-one".