1221999912 has 288 divisors, whose sum is σ = 4151534400. Its totient is φ = 326229120.

The previous prime is 1221999907. The next prime is 1221999937. The reversal of 1221999912 is 2199991221.

It is a nude number because it is divisible by every one of its digits.

Its product of digits (52488) is a multiple of the sum of its prime divisors (72).

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 39419337 + ... + 39419367.

It is an arithmetic number, because the mean of its divisors is an integer number (14415050).

Almost surely, 2^1221999912 is an apocalyptic number.

1221999912 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221999912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2075767200).

1221999912 is an abundant number, since it is smaller than the sum of its proper divisors (2929534488).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221999912 is a wasteful number, since it uses less digits than its factorization.

1221999912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142 (or 72 counting only the distinct ones).

The product of its digits is 52488, while the sum is 45.

The square root of 1221999912 is about 34957.1153272120. The cubic root of 1221999912 is about 1069.1132817343.

The spelling of 1221999912 in words is "one billion, two hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred twelve".