20121221001 has 16 divisors (see below), whose sum is σ = 30684847104. Its totient is φ = 11488863504.

The previous prime is 20121220981. The next prime is 20121221033. The reversal of 20121221001 is 10012212102.

It is not a de Polignac number, because 20121221001 - 2¹⁷ = 20121089929 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20121221041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 346461 + ... + 400346.

It is an arithmetic number, because the mean of its divisors is an integer number (1917802944).

Almost surely, 2^20121221001 is an apocalyptic number.

20121221001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20121221001 is a deficient number, since it is larger than the sum of its proper divisors (10563626103).

20121221001 is a wasteful number, since it uses less digits than its factorization.

20121221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 748100.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 20121221001 its reverse (10012212102), we get a palindrome (30133433103).

The spelling of 20121221001 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, one".