21611203 has 2 divisors, whose sum is σ = 21611204. Its totient is φ = 21611202.

The previous prime is 21611197. The next prime is 21611221. The reversal of 21611203 is 30211612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21611203 - 2⁵ = 21611171 is a prime.

It is not a weakly prime, because it can be changed into another prime (21611243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10805601 + 10805602.

It is an arithmetic number, because the mean of its divisors is an integer number (10805602).

Almost surely, 2^21611203 is an apocalyptic number.

21611203 is a deficient number, since it is larger than the sum of its proper divisors (1).

21611203 is an equidigital number, since it uses as much as digits as its factorization.

21611203 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21611203 is about 4648.7851101121. The cubic root of 21611203 is about 278.5434695837.

Adding to 21611203 its reverse (30211612), we get a palindrome (51822815).

It can be divided in two parts, 2161 and 1203, that added together give a square (3364 = 58²).

The spelling of 21611203 in words is "twenty-one million, six hundred eleven thousand, two hundred three".