2001212021221 has 24 divisors (see below), whose sum is σ = 2418216580032. Its totient is φ = 1621386849600.

The previous prime is 2001212021219. The next prime is 2001212021227. The reversal of 2001212021221 is 1221202121002.

It is a happy number.

It is not a de Polignac number, because 2001212021221 - 2¹ = 2001212021219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2001212021195 and 2001212021204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001212021227) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3169920 + ... + 3748441.

It is an arithmetic number, because the mean of its divisors is an integer number (100759024168).

Almost surely, 2^{2001212021221} is an apocalyptic number.

It is an amenable number.

2001212021221 is a deficient number, since it is larger than the sum of its proper divisors (417004558811).

2001212021221 is an equidigital number, since it uses as much as digits as its factorization.

2001212021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6918473 (or 6918442 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 2001212021221 its reverse (1221202121002), we get a palindrome (3222414142223).

The spelling of 2001212021221 in words is "two trillion, one billion, two hundred twelve million, twenty-one thousand, two hundred twenty-one".