202100021 has 4 divisors (see below), whose sum is σ = 202135500. Its totient is φ = 202064544.

The previous prime is 202099993. The next prime is 202100033. The reversal of 202100021 is 120001202.

202100021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 56415121 + 145684900 = 7511^2 + 12070^2 .

It is a cyclic number.

It is not a de Polignac number, because 202100021 - 2¹⁰ = 202098997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 202099981 and 202100008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (202100051) 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, 7046 + ... + 21303.

It is an arithmetic number, because the mean of its divisors is an integer number (50533875).

Almost surely, 2^202100021 is an apocalyptic number.

It is an amenable number.

202100021 is a deficient number, since it is larger than the sum of its proper divisors (35479).

202100021 is an equidigital number, since it uses as much as digits as its factorization.

202100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35478.

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

The square root of 202100021 is about 14216.1886945834. The cubic root of 202100021 is about 586.8432580407.

Adding to 202100021 its reverse (120001202), we get a palindrome (322101223).

The spelling of 202100021 in words is "two hundred two million, one hundred thousand, twenty-one".