21205021201 has 16 divisors (see below), whose sum is σ = 26540841600. Its totient is φ = 16493228928.

The previous prime is 21205021181. The next prime is 21205021207. The reversal of 21205021201 is 10212050212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21205021201 - 2⁹ = 21205020689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21205021207) 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, 1969396 + ... + 1980133.

It is an arithmetic number, because the mean of its divisors is an integer number (1658802600).

Almost surely, 2^21205021201 is an apocalyptic number.

It is an amenable number.

21205021201 is a deficient number, since it is larger than the sum of its proper divisors (5335820399).

21205021201 is a wasteful number, since it uses less digits than its factorization.

21205021201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3949608.

The product of its (nonzero) digits is 80, while the sum is 16.

Adding to 21205021201 its reverse (10212050212), we get a palindrome (31417071413).

The spelling of 21205021201 in words is "twenty-one billion, two hundred five million, twenty-one thousand, two hundred one".