21345173 has 4 divisors (see below), whose sum is σ = 22273248. Its totient is φ = 20417100.

The previous prime is 21345119. The next prime is 21345187. The reversal of 21345173 is 37154312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21345173 - 2¹² = 21341077 is a prime.

It is a super-3 number, since 3×21345173³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21344173) 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 in 3 ways as a sum of consecutive naturals, for example, 464003 + ... + 464048.

It is an arithmetic number, because the mean of its divisors is an integer number (5568312).

Almost surely, 2^21345173 is an apocalyptic number.

21345173 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21345173 is a deficient number, since it is larger than the sum of its proper divisors (928075).

21345173 is an equidigital number, since it uses as much as digits as its factorization.

21345173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 928074.

The product of its digits is 2520, while the sum is 26.

The square root of 21345173 is about 4620.0836572512. The cubic root of 21345173 is about 277.3958075414.

Adding to 21345173 its reverse (37154312), we get a palindrome (58499485).

The spelling of 21345173 in words is "twenty-one million, three hundred forty-five thousand, one hundred seventy-three".