1221839 has 4 divisors (see below), whose sum is σ = 1239120. Its totient is φ = 1204560.

The previous prime is 1221823. The next prime is 1221853. The reversal of 1221839 is 9381221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9381221 = 157 ⋅59753.

It is a cyclic number.

It is not a de Polignac number, because 1221839 - 2⁴ = 1221823 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 (1221239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8534 + ... + 8675.

It is an arithmetic number, because the mean of its divisors is an integer number (309780).

2^1221839 is an apocalyptic number.

1221839 is a deficient number, since it is larger than the sum of its proper divisors (17281).

1221839 is an equidigital number, since it uses as much as digits as its factorization.

1221839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17280.

The product of its digits is 864, while the sum is 26.

The square root of 1221839 is about 1105.3682644259. The cubic root of 1221839 is about 106.9066353005.

The spelling of 1221839 in words is "one million, two hundred twenty-one thousand, eight hundred thirty-nine".