21725173 has 4 divisors (see below), whose sum is σ = 21928320. Its totient is φ = 21522028.

The previous prime is 21725161. The next prime is 21725183. The reversal of 21725173 is 37152712.

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 a cyclic number.

It is not a de Polignac number, because 21725173 - 2¹⁷ = 21594101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21725183) 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, 101413 + ... + 101626.

It is an arithmetic number, because the mean of its divisors is an integer number (5482080).

Almost surely, 2^21725173 is an apocalyptic number.

It is an amenable number.

21725173 is a deficient number, since it is larger than the sum of its proper divisors (203147).

21725173 is a wasteful number, since it uses less digits than its factorization.

21725173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203146.

The product of its digits is 2940, while the sum is 28.

The square root of 21725173 is about 4661.0270327472. The cubic root of 21725173 is about 279.0322586168.

Adding to 21725173 its reverse (37152712), we get a palindrome (58877885).

The spelling of 21725173 in words is "twenty-one million, seven hundred twenty-five thousand, one hundred seventy-three".