1221229909 has 4 divisors (see below), whose sum is σ = 1225131916. Its totient is φ = 1217327904.

The previous prime is 1221229907. The next prime is 1221229927. The reversal of 1221229909 is 9099221221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 335988900 + 885241009 = 18330^2 + 29753^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221229909 - 2¹ = 1221229907 is a prime.

It is a super-2 number, since 2×1221229909² = 2982804981272296562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221229907) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1950534 + ... + 1951159.

It is an arithmetic number, because the mean of its divisors is an integer number (306282979).

Almost surely, 2^1221229909 is an apocalyptic number.

It is an amenable number.

1221229909 is a deficient number, since it is larger than the sum of its proper divisors (3902007).

1221229909 is an equidigital number, since it uses as much as digits as its factorization.

1221229909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3902006.

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 1221229909 is about 34946.1000542264. The cubic root of 1221229909 is about 1068.8886790440. Note that the first 3 decimals are identical.

The spelling of 1221229909 in words is "one billion, two hundred twenty-one million, two hundred twenty-nine thousand, nine hundred nine".