2001221210121 has 64 divisors (see below), whose sum is σ = 3378697256448. Its totient is φ = 1027439382528.

The previous prime is 2001221210089. The next prime is 2001221210143. The reversal of 2001221210121 is 1210121221002.

It is not a de Polignac number, because 2001221210121 - 2⁵ = 2001221210089 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2001221210121.

It is not an unprimeable number, because it can be changed into a prime (2001221210161) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 729210 + ... + 2129363.

It is an arithmetic number, because the mean of its divisors is an integer number (52792144632).

Almost surely, 2^{2001221210121} is an apocalyptic number.

2001221210121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2001221210121 is a deficient number, since it is larger than the sum of its proper divisors (1377476046327).

2001221210121 is a wasteful number, since it uses less digits than its factorization.

2001221210121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2858690.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 2001221210121 its reverse (1210121221002), we get a palindrome (3211342431123).

It can be divided in two parts, 2001 and 221210121, that added together give a palindrome (221212122).

The spelling of 2001221210121 in words is "two trillion, one billion, two hundred twenty-one million, two hundred ten thousand, one hundred twenty-one".