21616201 has 2 divisors, whose sum is σ = 21616202. Its totient is φ = 21616200.

The previous prime is 21616187. The next prime is 21616211. The reversal of 21616201 is 10261612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16321600 + 5294601 = 4040^2 + 2301^2 .

It is a cyclic number.

It is not a de Polignac number, because 21616201 - 2⁵ = 21616169 is a prime.

It is not a weakly prime, because it can be changed into another prime (21616211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808100 + 10808101.

It is an arithmetic number, because the mean of its divisors is an integer number (10808101).

Almost surely, 2^21616201 is an apocalyptic number.

It is an amenable number.

21616201 is a deficient number, since it is larger than the sum of its proper divisors (1).

21616201 is an equidigital number, since it uses as much as digits as its factorization.

21616201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21616201 is about 4649.3226388368. The cubic root of 21616201 is about 278.5649407462.

Adding to 21616201 its reverse (10261612), we get a palindrome (31877813).

The spelling of 21616201 in words is "twenty-one million, six hundred sixteen thousand, two hundred one".