21947173 has 2 divisors, whose sum is σ = 21947174. Its totient is φ = 21947172.

The previous prime is 21947161. The next prime is 21947197. The reversal of 21947173 is 37174912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11175649 + 10771524 = 3343^2 + 3282^2 .

It is a cyclic number.

It is not a de Polignac number, because 21947173 - 2²¹ = 19850021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21947273) 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, 10973586 + 10973587.

It is an arithmetic number, because the mean of its divisors is an integer number (10973587).

Almost surely, 2^21947173 is an apocalyptic number.

It is an amenable number.

21947173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21947173 is an equidigital number, since it uses as much as digits as its factorization.

21947173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10584, while the sum is 34.

The square root of 21947173 is about 4684.7809980830. The cubic root of 21947173 is about 279.9794755364.

The spelling of 21947173 in words is "twenty-one million, nine hundred forty-seven thousand, one hundred seventy-three".