2101210021 has 4 divisors (see below), whose sum is σ = 2104942752. Its totient is φ = 2097477292.

The previous prime is 2101210009. The next prime is 2101210031. The reversal of 2101210021 is 1200121012.

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 2101210021 - 2²⁹ = 1564339109 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 (2101210031) 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, 1865521 + ... + 1866646.

It is an arithmetic number, because the mean of its divisors is an integer number (526235688).

Almost surely, 2^2101210021 is an apocalyptic number.

It is an amenable number.

2101210021 is a deficient number, since it is larger than the sum of its proper divisors (3732731).

2101210021 is an equidigital number, since it uses as much as digits as its factorization.

2101210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3732730.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 2101210021 is about 45838.9574597852. The cubic root of 2101210021 is about 1280.8250745374.

Adding to 2101210021 its reverse (1200121012), we get a palindrome (3301331033).

The spelling of 2101210021 in words is "two billion, one hundred one million, two hundred ten thousand, twenty-one".