20122100021 has 4 divisors (see below), whose sum is σ = 20122384044. Its totient is φ = 20121816000.

The previous prime is 20122099981. The next prime is 20122100029. The reversal of 20122100021 is 12000122102.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 6576399025 + 13545700996 = 81095^2 + 116386^2 .

It is a cyclic number.

It is not a de Polignac number, because 20122100021 - 2¹⁸ = 20121837877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20122099975 and 20122100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20122100029) 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, 60941 + ... + 209661.

It is an arithmetic number, because the mean of its divisors is an integer number (5030596011).

Almost surely, 2^20122100021 is an apocalyptic number.

It is an amenable number.

20122100021 is a deficient number, since it is larger than the sum of its proper divisors (284023).

20122100021 is a wasteful number, since it uses less digits than its factorization.

20122100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284022.

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

Adding to 20122100021 its reverse (12000122102), we get a palindrome (32122222123).

The spelling of 20122100021 in words is "twenty billion, one hundred twenty-two million, one hundred thousand, twenty-one".