20021012021 has 4 divisors (see below), whose sum is σ = 20562120492. Its totient is φ = 19479903552.

The previous prime is 20021012003. The next prime is 20021012041. The reversal of 20021012021 is 12021012002.

It is a happy number.

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 19276267921 + 744744100 = 138839^2 + 27290^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021012021 - 2⁶ = 20021011957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021011993 and 20021012011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021012041) 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, 270554180 + ... + 270554253.

It is an arithmetic number, because the mean of its divisors is an integer number (5140530123).

Almost surely, 2^20021012021 is an apocalyptic number.

It is an amenable number.

20021012021 is a deficient number, since it is larger than the sum of its proper divisors (541108471).

20021012021 is an equidigital number, since it uses as much as digits as its factorization.

20021012021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541108470.

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

Adding to 20021012021 its reverse (12021012002), we get a palindrome (32042024023).

The spelling of 20021012021 in words is "twenty billion, twenty-one million, twelve thousand, twenty-one".