210020210021 has 4 divisors (see below), whose sum is σ = 210105137772. Its totient is φ = 209935282272.

The previous prime is 210020209961. The next prime is 210020210053. The reversal of 210020210021 is 120012020012.

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 187605928225 + 22414281796 = 433135^2 + 149714^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-210020210021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 210020209984 and 210020210011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210020270021) 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, 42460166 + ... + 42465111.

It is an arithmetic number, because the mean of its divisors is an integer number (52526284443).

Almost surely, 2^210020210021 is an apocalyptic number.

It is an amenable number.

210020210021 is a deficient number, since it is larger than the sum of its proper divisors (84927751).

210020210021 is an equidigital number, since it uses as much as digits as its factorization.

210020210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84927750.

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

Adding to 210020210021 its reverse (120012020012), we get a palindrome (330032230033).

The spelling of 210020210021 in words is "two hundred ten billion, twenty million, two hundred ten thousand, twenty-one".