21020101021 has 4 divisors (see below), whose sum is σ = 21021343200. Its totient is φ = 21018858844.

The previous prime is 21020100973. The next prime is 21020101073. The reversal of 21020101021 is 12010102012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21020101021 - 2³¹ = 18872617373 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020100989 and 21020101007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020101321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 595351 + ... + 629668.

It is an arithmetic number, because the mean of its divisors is an integer number (5255335800).

Almost surely, 2^21020101021 is an apocalyptic number.

It is an amenable number.

21020101021 is a deficient number, since it is larger than the sum of its proper divisors (1242179).

21020101021 is a wasteful number, since it uses less digits than its factorization.

21020101021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1242178.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21020101021 its reverse (12010102012), we get a palindrome (33030203033).

Subtracting from 21020101021 its reverse (12010102012), we obtain a palindrome (9009999009).

The spelling of 21020101021 in words is "twenty-one billion, twenty million, one hundred one thousand, twenty-one".