21673145 has 8 divisors (see below), whose sum is σ = 28008456. Its totient is φ = 16004736.

The previous prime is 21673139. The next prime is 21673159. The reversal of 21673145 is 54137612.

It can be written as a sum of positive squares in 4 ways, for example, as 32041 + 21641104 = 179^2 + 4652^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21673145 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 166652 + ... + 166781.

It is an arithmetic number, because the mean of its divisors is an integer number (3501057).

Almost surely, 2^21673145 is an apocalyptic number.

It is an amenable number.

21673145 is a deficient number, since it is larger than the sum of its proper divisors (6335311).

21673145 is a wasteful number, since it uses less digits than its factorization.

21673145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333451.

The product of its digits is 5040, while the sum is 29.

The square root of 21673145 is about 4655.4425138756. The cubic root of 21673145 is about 278.8093360383.

The spelling of 21673145 in words is "twenty-one million, six hundred seventy-three thousand, one hundred forty-five".