20000021021 has 4 divisors (see below), whose sum is σ = 20134249500. Its totient is φ = 19865792544.

The previous prime is 20000021009. The next prime is 20000021023. The reversal of 20000021021 is 12012000002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10451995225 + 9548025796 = 102235^2 + 97714^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20000021021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20000021023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67114016 + ... + 67114313.

It is an arithmetic number, because the mean of its divisors is an integer number (5033562375).

Almost surely, 2^20000021021 is an apocalyptic number.

It is an amenable number.

20000021021 is a deficient number, since it is larger than the sum of its proper divisors (134228479).

20000021021 is a wasteful number, since it uses less digits than its factorization.

20000021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134228478.

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

Adding to 20000021021 its reverse (12012000002), we get a palindrome (32012021023).

The spelling of 20000021021 in words is "twenty billion, twenty-one thousand, twenty-one".