21020020100021 has 8 divisors (see below), whose sum is σ = 21376475959200. Its totient is φ = 20663570385360.

The previous prime is 21020020099927. The next prime is 21020020100059. The reversal of 21020020100021 is 12000102002012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21020020100021 - 2¹⁰ = 21020020098997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020020099975 and 21020020100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020020180021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5646086 + ... + 8597576.

It is an arithmetic number, because the mean of its divisors is an integer number (2672059494900).

Almost surely, 2^{21020020100021} is an apocalyptic number.

It is an amenable number.

21020020100021 is a deficient number, since it is larger than the sum of its proper divisors (356455859179).

21020020100021 is a wasteful number, since it uses less digits than its factorization.

21020020100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3072259.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21020020100021 its reverse (12000102002012), we get a palindrome (33020122102033).

The spelling of 21020020100021 in words is "twenty-one trillion, twenty billion, twenty million, one hundred thousand, twenty-one".