21202012021 has 16 divisors (see below), whose sum is σ = 22033186560. Its totient is φ = 20387727360.

The previous prime is 21202012003. The next prime is 21202012037. The reversal of 21202012021 is 12021020212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21202012021 - 2¹³ = 21202003829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202011992 and 21202012010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202012121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1190301 + ... + 1207981.

It is an arithmetic number, because the mean of its divisors is an integer number (1377074160).

Almost surely, 2^21202012021 is an apocalyptic number.

It is an amenable number.

21202012021 is a deficient number, since it is larger than the sum of its proper divisors (831174539).

21202012021 is a wasteful number, since it uses less digits than its factorization.

21202012021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18156.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21202012021 its reverse (12021020212), we get a palindrome (33223032233).

The spelling of 21202012021 in words is "twenty-one billion, two hundred two million, twelve thousand, twenty-one".