21550201 has 2 divisors, whose sum is σ = 21550202. Its totient is φ = 21550200.

The previous prime is 21550183. The next prime is 21550229. The reversal of 21550201 is 10205512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13512976 + 8037225 = 3676^2 + 2835^2 .

It is a cyclic number.

It is not a de Polignac number, because 21550201 - 2⁷ = 21550073 is a prime.

It is a super-2 number, since 2×21550201² = 928822326280802, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21550231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775100 + 10775101.

It is an arithmetic number, because the mean of its divisors is an integer number (10775101).

Almost surely, 2^21550201 is an apocalyptic number.

It is an amenable number.

21550201 is a deficient number, since it is larger than the sum of its proper divisors (1).

21550201 is an equidigital number, since it uses as much as digits as its factorization.

21550201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 21550201 is about 4642.2194045521. The cubic root of 21550201 is about 278.2811408066.

Adding to 21550201 its reverse (10205512), we get a palindrome (31755713).

The spelling of 21550201 in words is "twenty-one million, five hundred fifty thousand, two hundred one".