21122173 has 4 divisors (see below), whose sum is σ = 21171388. Its totient is φ = 21072960.

The previous prime is 21122161. The next prime is 21122183. The reversal of 21122173 is 37122112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1435204 + 19686969 = 1198^2 + 4437^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122173 - 2¹⁷ = 20991101 is a prime.

It is a super-2 number, since 2×21122173² = 892292384483858, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21122173.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122183) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23958 + ... + 24823.

It is an arithmetic number, because the mean of its divisors is an integer number (5292847).

Almost surely, 2^21122173 is an apocalyptic number.

It is an amenable number.

21122173 is a deficient number, since it is larger than the sum of its proper divisors (49215).

21122173 is an equidigital number, since it uses as much as digits as its factorization.

21122173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49214.

The product of its digits is 168, while the sum is 19.

The square root of 21122173 is about 4595.8865303660. The cubic root of 21122173 is about 276.4264088941.

Adding to 21122173 its reverse (37122112), we get a palindrome (58244285).

The spelling of 21122173 in words is "twenty-one million, one hundred twenty-two thousand, one hundred seventy-three".