21022100021 has 16 divisors (see below), whose sum is σ = 23224274304. Its totient is φ = 18905793984.

The previous prime is 21022100009. The next prime is 21022100053. The reversal of 21022100021 is 12000122012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21022100021 - 2¹⁸ = 21021837877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21022099975 and 21022100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022100221) 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, 174560 + ... + 269286.

It is an arithmetic number, because the mean of its divisors is an integer number (1451517144).

Almost surely, 2^21022100021 is an apocalyptic number.

It is an amenable number.

21022100021 is a deficient number, since it is larger than the sum of its proper divisors (2202174283).

21022100021 is a wasteful number, since it uses less digits than its factorization.

21022100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95180.

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

Adding to 21022100021 its reverse (12000122012), we get a palindrome (33022222033).

The spelling of 21022100021 in words is "twenty-one billion, twenty-two million, one hundred thousand, twenty-one".