1221043999 has 8 divisors (see below), whose sum is σ = 1419131520. Its totient is φ = 1028869656.

The previous prime is 1221043991. The next prime is 1221044003. The reversal of 1221043999 is 9993401221.

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 1221043999 - 2³ = 1221043991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221043991) 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 7 ways as a sum of consecutive naturals, for example, 1477849 + ... + 1478674.

It is an arithmetic number, because the mean of its divisors is an integer number (177391440).

Almost surely, 2^1221043999 is an apocalyptic number.

1221043999 is a deficient number, since it is larger than the sum of its proper divisors (198087521).

1221043999 is an equidigital number, since it uses as much as digits as its factorization.

1221043999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2956589.

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 1221043999 is about 34943.4399995192. The cubic root of 1221043999 is about 1068.8344366835.

The spelling of 1221043999 in words is "one billion, two hundred twenty-one million, forty-three thousand, nine hundred ninety-nine".