21171673 has 2 divisors, whose sum is σ = 21171674. Its totient is φ = 21171672.

The previous prime is 21171671. The next prime is 21171701. The reversal of 21171673 is 37617112.

It is an a-pointer prime, because the next prime (21171701) can be obtained adding 21171673 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19998784 + 1172889 = 4472^2 + 1083^2 .

It is a cyclic number.

It is not a de Polignac number, because 21171673 - 2¹ = 21171671 is a prime.

Together with 21171671, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21171671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585836 + 10585837.

It is an arithmetic number, because the mean of its divisors is an integer number (10585837).

Almost surely, 2^21171673 is an apocalyptic number.

It is an amenable number.

21171673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21171673 is an equidigital number, since it uses as much as digits as its factorization.

21171673 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1764, while the sum is 28.

The square root of 21171673 is about 4601.2686294108. The cubic root of 21171673 is about 276.6421763454.

Adding to 21171673 its reverse (37617112), we get a palindrome (58788785).

The spelling of 21171673 in words is "twenty-one million, one hundred seventy-one thousand, six hundred seventy-three".