1221783909 has 4 divisors (see below), whose sum is σ = 1629045216. Its totient is φ = 814522604.

The previous prime is 1221783907. The next prime is 1221784001. The reversal of 1221783909 is 9093871221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9093871221 = 3 ⋅3031290407.

It is a cyclic number.

It is not a de Polignac number, because 1221783909 - 2¹ = 1221783907 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221783907) 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, 203630649 + ... + 203630654.

It is an arithmetic number, because the mean of its divisors is an integer number (407261304).

Almost surely, 2^1221783909 is an apocalyptic number.

It is an amenable number.

1221783909 is a deficient number, since it is larger than the sum of its proper divisors (407261307).

1221783909 is an equidigital number, since it uses as much as digits as its factorization.

1221783909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407261306.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 1221783909 is about 34954.0256479851. The cubic root of 1221783909 is about 1069.0502851983.

The spelling of 1221783909 in words is "one billion, two hundred twenty-one million, seven hundred eighty-three thousand, nine hundred nine".