20001100021 has 4 divisors (see below), whose sum is σ = 22858400032. Its totient is φ = 17143800012.

The previous prime is 20001100019. The next prime is 20001100033. The reversal of 20001100021 is 12000110002.

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 20001100021 - 2¹ = 20001100019 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (7), and also a Moran number because the ratio is a prime number: 2857300003 = 20001100021 / (2 + 0 + 0 + 0 + 1 + 1 + 0 + 0 + 0 + 2 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20001099977 and 20001100013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001100001) 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, 1428649995 + ... + 1428650008.

It is an arithmetic number, because the mean of its divisors is an integer number (5714600008).

Almost surely, 2^20001100021 is an apocalyptic number.

It is an amenable number.

20001100021 is a deficient number, since it is larger than the sum of its proper divisors (2857300011).

20001100021 is an equidigital number, since it uses as much as digits as its factorization.

20001100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2857300010.

The product of its (nonzero) digits is 4, while the sum is 7.

Adding to 20001100021 its reverse (12000110002), we get a palindrome (32001210023).

The spelling of 20001100021 in words is "twenty billion, one million, one hundred thousand, twenty-one".