21050173 has 2 divisors, whose sum is σ = 21050174. Its totient is φ = 21050172.

The previous prime is 21050171. The next prime is 21050203. The reversal of 21050173 is 37105012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21040569 + 9604 = 4587^2 + 98^2 .

It is a cyclic number.

It is not a de Polignac number, because 21050173 - 2¹ = 21050171 is a prime.

Together with 21050171, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21050173.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21050171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10525086 + 10525087.

It is an arithmetic number, because the mean of its divisors is an integer number (10525087).

Almost surely, 2^21050173 is an apocalyptic number.

It is an amenable number.

21050173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21050173 is an equidigital number, since it uses as much as digits as its factorization.

21050173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 21050173 is about 4588.0467521594. The cubic root of 21050173 is about 276.1119627314. Note that the first 3 decimals are identical.

Adding to 21050173 its reverse (37105012), we get a palindrome (58155185).

The spelling of 21050173 in words is "twenty-one million, fifty thousand, one hundred seventy-three".