21097173 has 4 divisors (see below), whose sum is σ = 28129568. Its totient is φ = 14064780.

The previous prime is 21097171. The next prime is 21097207. The reversal of 21097173 is 37179012.

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 21097173 - 2¹ = 21097171 is a prime.

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 21097173.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21097171) 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, 3516193 + ... + 3516198.

It is an arithmetic number, because the mean of its divisors is an integer number (7032392).

Almost surely, 2^21097173 is an apocalyptic number.

It is an amenable number.

21097173 is a deficient number, since it is larger than the sum of its proper divisors (7032395).

21097173 is an equidigital number, since it uses as much as digits as its factorization.

21097173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7032394.

The product of its (nonzero) digits is 2646, while the sum is 30.

The square root of 21097173 is about 4593.1659016413. The cubic root of 21097173 is about 276.3173072961.

The spelling of 21097173 in words is "twenty-one million, ninety-seven thousand, one hundred seventy-three".