1221000209 has 16 divisors (see below), whose sum is σ = 1435783104. Its totient is φ = 1023672000.

The previous prime is 1221000203. The next prime is 1221000227. The reversal of 1221000209 is 9020001221.

It is not a de Polignac number, because 1221000209 - 2⁸ = 1220999953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221000203) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 182762 + ... + 189324.

It is an arithmetic number, because the mean of its divisors is an integer number (89736444).

Almost surely, 2^1221000209 is an apocalyptic number.

It is an amenable number.

1221000209 is a deficient number, since it is larger than the sum of its proper divisors (214782895).

1221000209 is a wasteful number, since it uses less digits than its factorization.

1221000209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7888.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 1221000209 is about 34942.8134099131. The cubic root of 1221000209 is about 1068.8216594155.

The spelling of 1221000209 in words is "one billion, two hundred twenty-one million, two hundred nine", and thus it is an aban number.