21002121210021 has 64 divisors (see below), whose sum is σ = 32911715622912. Its totient is φ = 11662833600000.

The previous prime is 21002121209989. The next prime is 21002121210043. The reversal of 21002121210021 is 12001212120012.

It is not a de Polignac number, because 21002121210021 - 2⁵ = 21002121209989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002121214021) 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, 2121207171 + ... + 2121217071.

It is an arithmetic number, because the mean of its divisors is an integer number (514245556608).

Almost surely, 2^{21002121210021} is an apocalyptic number.

21002121210021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21002121210021 is a deficient number, since it is larger than the sum of its proper divisors (11909594412891).

21002121210021 is a wasteful number, since it uses less digits than its factorization.

21002121210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19314.

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

Adding to 21002121210021 its reverse (12001212120012), we get a palindrome (33003333330033).

Subtracting from 21002121210021 its reverse (12001212120012), we obtain a palindrome (9000909090009).

The spelling of 21002121210021 in words is "twenty-one trillion, two billion, one hundred twenty-one million, two hundred ten thousand, twenty-one".