20201210021 has 4 divisors (see below), whose sum is σ = 20897803500. Its totient is φ = 19504616544.

The previous prime is 20201209981. The next prime is 20201210033. The reversal of 20201210021 is 12001210202.

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 9194892100 + 11006317921 = 95890^2 + 104911^2 .

It is a cyclic number.

It is not a de Polignac number, because 20201210021 - 2³⁴ = 3021340837 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20201209984 and 20201210011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20201210521) 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, 348296696 + ... + 348296753.

It is an arithmetic number, because the mean of its divisors is an integer number (5224450875).

Almost surely, 2^20201210021 is an apocalyptic number.

It is an amenable number.

20201210021 is a deficient number, since it is larger than the sum of its proper divisors (696593479).

20201210021 is an equidigital number, since it uses as much as digits as its factorization.

20201210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 696593478.

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

Adding to 20201210021 its reverse (12001210202), we get a palindrome (32202420223).

The spelling of 20201210021 in words is "twenty billion, two hundred one million, two hundred ten thousand, twenty-one".