21001220201 has 16 divisors (see below), whose sum is σ = 23851208640. Its totient is φ = 18331375680.

The previous prime is 21001220189. The next prime is 21001220243. The reversal of 21001220201 is 10202210012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21001220201 - 2³⁰ = 19927478377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001229201) 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, 55046 + ... + 212208.

It is an arithmetic number, because the mean of its divisors is an integer number (1490700540).

Almost surely, 2^21001220201 is an apocalyptic number.

It is an amenable number.

21001220201 is a deficient number, since it is larger than the sum of its proper divisors (2849988439).

21001220201 is a wasteful number, since it uses less digits than its factorization.

21001220201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157736.

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

Adding to 21001220201 its reverse (10202210012), we get a palindrome (31203430213).

The spelling of 21001220201 in words is "twenty-one billion, one million, two hundred twenty thousand, two hundred one".