21000002002021 has 72 divisors (see below), whose sum is σ = 26604051729480. Its totient is φ = 16527660119040.

The previous prime is 21000002002013. The next prime is 21000002002037. The reversal of 21000002002021 is 12020020000012.

It can be written as a sum of positive squares in 12 ways, for example, as 17633826540225 + 3366175461796 = 4199265^2 + 1834714^2 .

It is not a de Polignac number, because 21000002002021 - 2³ = 21000002002013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000002001989 and 21000002002007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000002002121) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 404652951 + ... + 404704843.

It is an arithmetic number, because the mean of its divisors is an integer number (369500718465).

Almost surely, 2^{21000002002021} is an apocalyptic number.

It is an amenable number.

21000002002021 is a deficient number, since it is larger than the sum of its proper divisors (5604049727459).

21000002002021 is an frugal number, since it uses more digits than its factorization.

21000002002021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52040 (or 51958 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21000002002021 its reverse (12020020000012), we get a palindrome (33020022002033).

The spelling of 21000002002021 in words is "twenty-one trillion, two million, two thousand, twenty-one".