21045172 has 12 divisors (see below), whose sum is σ = 37074016. Its totient is φ = 10452600.

The previous prime is 21045151. The next prime is 21045197. The reversal of 21045172 is 27154012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16818 + ... + 18025.

Almost surely, 2^21045172 is an apocalyptic number.

It is an amenable number.

21045172 is a deficient number, since it is larger than the sum of its proper divisors (16028844).

21045172 is a wasteful number, since it uses less digits than its factorization.

21045172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34998 (or 34996 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21045172 is about 4587.5017166209. The cubic root of 21045172 is about 276.0900952105.

Adding to 21045172 its reverse (27154012), we get a palindrome (48199184).

The spelling of 21045172 in words is "twenty-one million, forty-five thousand, one hundred seventy-two".