21174221 has 2 divisors, whose sum is σ = 21174222. Its totient is φ = 21174220.

The previous prime is 21174217. The next prime is 21174229. The reversal of 21174221 is 12247112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18966025 + 2208196 = 4355^2 + 1486^2 .

It is a cyclic number.

It is not a de Polignac number, because 21174221 - 2² = 21174217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21174193 and 21174202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21174229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10587110 + 10587111.

It is an arithmetic number, because the mean of its divisors is an integer number (10587111).

Almost surely, 2^21174221 is an apocalyptic number.

It is an amenable number.

21174221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21174221 is an equidigital number, since it uses as much as digits as its factorization.

21174221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 224, while the sum is 20.

The square root of 21174221 is about 4601.5455012419. The cubic root of 21174221 is about 276.6532738150.

The spelling of 21174221 in words is "twenty-one million, one hundred seventy-four thousand, two hundred twenty-one".