1221909 has 32 divisors (see below), whose sum is σ = 1975680. Its totient is φ = 663552.

The previous prime is 1221907. The next prime is 1221917. The reversal of 1221909 is 9091221.

It is not a de Polignac number, because 1221909 - 2¹ = 1221907 is a prime.

1221909 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221907) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12549 + ... + 12645.

It is an arithmetic number, because the mean of its divisors is an integer number (61740).

2^1221909 is an apocalyptic number.

1221909 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1221909 is a deficient number, since it is larger than the sum of its proper divisors (753771).

1221909 is a wasteful number, since it uses less digits than its factorization.

1221909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149.

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

The square root of 1221909 is about 1105.3999276280. The cubic root of 1221909 is about 106.9086768465.

The spelling of 1221909 in words is "one million, two hundred twenty-one thousand, nine hundred nine".