1221311309 has 16 divisors (see below), whose sum is σ = 1306853376. Its totient is φ = 1139410800.

The previous prime is 1221311261. The next prime is 1221311341. The reversal of 1221311309 is 9031131221.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221311309 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221311359) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 91364 + ... + 103874.

It is an arithmetic number, because the mean of its divisors is an integer number (81678336).

Almost surely, 2^1221311309 is an apocalyptic number.

It is an amenable number.

1221311309 is a deficient number, since it is larger than the sum of its proper divisors (85542067).

1221311309 is a wasteful number, since it uses less digits than its factorization.

1221311309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12656.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 1221311309 is about 34947.2646855230. The cubic root of 1221311309 is about 1068.9124271264.

The spelling of 1221311309 in words is "one billion, two hundred twenty-one million, three hundred eleven thousand, three hundred nine".