1209921 has 8 divisors (see below), whose sum is σ = 1647744. Its totient is φ = 789360.

The previous prime is 1209889. The next prime is 1209931. The reversal of 1209921 is 1299021.

1209921 = T₂₀₃ + T₂₀₄ + ... + T₂₄₉.

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

It is not a de Polignac number, because 1209921 - 2⁵ = 1209889 is a prime.

1209921 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1209891 and 1209900.

It is not an unprimeable number, because it can be changed into a prime (1209931) 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, 4150 + ... + 4431.

It is an arithmetic number, because the mean of its divisors is an integer number (205968).

2^1209921 is an apocalyptic number.

It is an amenable number.

1209921 is a deficient number, since it is larger than the sum of its proper divisors (437823).

1209921 is an equidigital number, since it uses as much as digits as its factorization.

1209921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8631.

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 1209921 is about 1099.9640903230. The cubic root of 1209921 is about 106.5579045469.

The spelling of 1209921 in words is "one million, two hundred nine thousand, nine hundred twenty-one".