1221199999 has 8 divisors (see below), whose sum is σ = 1238412672. Its totient is φ = 1204047000.

The previous prime is 1221199963. The next prime is 1221200011. The reversal of 1221199999 is 9999911221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221199999 - 2¹⁵ = 1221167231 is a prime.

It is a Duffinian number.

1221199999 is a modest number, since divided by 99999 gives 12211 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221199949) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27124 + ... + 56374.

It is an arithmetic number, because the mean of its divisors is an integer number (154801584).

Almost surely, 2^1221199999 is an apocalyptic number.

1221199999 is a deficient number, since it is larger than the sum of its proper divisors (17212673).

1221199999 is an equidigital number, since it uses as much as digits as its factorization.

1221199999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29837.

The product of its digits is 236196, while the sum is 52.

The square root of 1221199999 is about 34945.6721068575. The cubic root of 1221199999 is about 1068.8799526715.

The spelling of 1221199999 in words is "one billion, two hundred twenty-one million, one hundred ninety-nine thousand, nine hundred ninety-nine".