21305201 has 4 divisors (see below), whose sum is σ = 21318900. Its totient is φ = 21291504.

The previous prime is 21305191. The next prime is 21305203. The reversal of 21305201 is 10250312.

It is a happy number.

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 14622976 + 6682225 = 3824^2 + 2585^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21305201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21305203) 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, 4166 + ... + 7743.

It is an arithmetic number, because the mean of its divisors is an integer number (5329725).

Almost surely, 2^21305201 is an apocalyptic number.

It is an amenable number.

21305201 is a deficient number, since it is larger than the sum of its proper divisors (13699).

21305201 is a wasteful number, since it uses less digits than its factorization.

21305201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13698.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21305201 is about 4615.7557344383. The cubic root of 21305201 is about 277.2225444220. Note that the first 3 decimals are identical.

Adding to 21305201 its reverse (10250312), we get a palindrome (31555513).

The spelling of 21305201 in words is "twenty-one million, three hundred five thousand, two hundred one".