1221309 has 6 divisors (see below), whose sum is σ = 1764126. Its totient is φ = 814200.

The previous prime is 1221299. The next prime is 1221373. The reversal of 1221309 is 9031221.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 864900 + 356409 = 930^2 + 597^2 .

It is not a de Polignac number, because 1221309 - 2⁹ = 1220797 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221291 and 1221300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221379) 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 5 ways as a sum of consecutive naturals, for example, 67842 + ... + 67859.

It is an arithmetic number, because the mean of its divisors is an integer number (294021).

2^1221309 is an apocalyptic number.

It is an amenable number.

1221309 is a deficient number, since it is larger than the sum of its proper divisors (542817).

1221309 is a wasteful number, since it uses less digits than its factorization.

1221309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135707 (or 135704 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 1221309 is about 1105.1284993158. The cubic root of 1221309 is about 106.8911753501.

It can be divided in two parts, 122 and 1309, that added together give a triangular number (1431 = T₅₃).

The spelling of 1221309 in words is "one million, two hundred twenty-one thousand, three hundred nine".