1221200001 has 36 divisors (see below), whose sum is σ = 2055261312. Its totient is φ = 696702384.

The previous prime is 1221199963. The next prime is 1221200011. The reversal of 1221200001 is 1000021221.

It is not a de Polignac number, because 1221200001 - 2⁷ = 1221199873 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1221200011) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 325800 + ... + 329526.

It is an arithmetic number, because the mean of its divisors is an integer number (57090592).

Almost surely, 2^1221200001 is an apocalyptic number.

It is an amenable number.

1221200001 is a deficient number, since it is larger than the sum of its proper divisors (834061311).

1221200001 is a wasteful number, since it uses less digits than its factorization.

1221200001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4490 (or 4480 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 1221200001 is about 34945.6721354734. The cubic root of 1221200001 is about 1068.8799532550.

Adding to 1221200001 its reverse (1000021221), we get a palindrome (2221221222).

The spelling of 1221200001 in words is "one billion, two hundred twenty-one million, two hundred thousand, one".