20101221010021 has 16 divisors (see below), whose sum is σ = 20833092371520. Its totient is φ = 19382921026560.

The previous prime is 20101221009997. The next prime is 20101221010043. The reversal of 20101221010021 is 12001012210102.

It is a cyclic number.

It is not a de Polignac number, because 20101221010021 - 2⁹ = 20101221009509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20101221009983 and 20101221010010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20101221019021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8157586 + ... + 10331923.

It is an arithmetic number, because the mean of its divisors is an integer number (1302068273220).

Almost surely, 2^{20101221010021} is an apocalyptic number.

It is an amenable number.

20101221010021 is a deficient number, since it is larger than the sum of its proper divisors (731871361499).

20101221010021 is a wasteful number, since it uses less digits than its factorization.

20101221010021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18489876.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 20101221010021 its reverse (12001012210102), we get a palindrome (32102233220123).

It can be divided in two parts, 20101 and 221010021, that added together give a palindrome (221030122).

The spelling of 20101221010021 in words is "twenty trillion, one hundred one billion, two hundred twenty-one million, ten thousand, twenty-one".