21876221 has 2 divisors, whose sum is σ = 21876222. Its totient is φ = 21876220.

The previous prime is 21876209. The next prime is 21876233. The reversal of 21876221 is 12267812.

It is a balanced prime because it is at equal distance from previous prime (21876209) and next prime (21876233).

It can be written as a sum of positive squares in only one way, i.e., 13980121 + 7896100 = 3739^2 + 2810^2 .

It is a cyclic number.

It is not a de Polignac number, because 21876221 - 2¹⁴ = 21859837 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21876241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10938110 + 10938111.

It is an arithmetic number, because the mean of its divisors is an integer number (10938111).

Almost surely, 2^21876221 is an apocalyptic number.

It is an amenable number.

21876221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21876221 is an equidigital number, since it uses as much as digits as its factorization.

21876221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2688, while the sum is 29.

The square root of 21876221 is about 4677.2022620366. The cubic root of 21876221 is about 279.6774389252.

The spelling of 21876221 in words is "twenty-one million, eight hundred seventy-six thousand, two hundred twenty-one".