21202021 has 8 divisors (see below), whose sum is σ = 22345344. Its totient is φ = 20077200.

The previous prime is 21202003. The next prime is 21202033. The reversal of 21202021 is 12020212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21202021 - 2⁷ = 21201893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201989 and 21202007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2241 + ... + 6886.

It is an arithmetic number, because the mean of its divisors is an integer number (2793168).

Almost surely, 2^21202021 is an apocalyptic number.

It is an amenable number.

21202021 is a deficient number, since it is larger than the sum of its proper divisors (1143323).

21202021 is a wasteful number, since it uses less digits than its factorization.

21202021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9251.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21202021 is about 4604.5652346340. The cubic root of 21202021 is about 276.7742951519.

Adding to 21202021 its reverse (12020212), we get a palindrome (33222233).

It can be divided in two parts, 2 and 1202021, that multiplied together give a palindrome (2404042).

The spelling of 21202021 in words is "twenty-one million, two hundred two thousand, twenty-one".