21173245 has 8 divisors (see below), whose sum is σ = 26902584. Its totient is φ = 15942144.

The previous prime is 21173233. The next prime is 21173263. The reversal of 21173245 is 54237112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4149369 + 17023876 = 2037^2 + 4126^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21173245 - 2⁹ = 21172733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124464 + ... + 124633.

It is an arithmetic number, because the mean of its divisors is an integer number (3362823).

Almost surely, 2^21173245 is an apocalyptic number.

It is an amenable number.

21173245 is a deficient number, since it is larger than the sum of its proper divisors (5729339).

21173245 is a wasteful number, since it uses less digits than its factorization.

21173245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249119.

The product of its digits is 1680, while the sum is 25.

The square root of 21173245 is about 4601.4394486943. The cubic root of 21173245 is about 276.6490230841.

The spelling of 21173245 in words is "twenty-one million, one hundred seventy-three thousand, two hundred forty-five".