21045171 has 8 divisors (see below), whose sum is σ = 32068864. Its totient is φ = 12025800.

The previous prime is 21045151. The next prime is 21045197. The reversal of 21045171 is 17154012.

It is a happy number.

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

It is not a de Polignac number, because 21045171 - 2⁵ = 21045139 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 1002151 = 21045171 / (2 + 1 + 0 + 4 + 5 + 1 + 7 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21045151) 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 7 ways as a sum of consecutive naturals, for example, 501055 + ... + 501096.

It is an arithmetic number, because the mean of its divisors is an integer number (4008608).

Almost surely, 2^21045171 is an apocalyptic number.

21045171 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21045171 is a deficient number, since it is larger than the sum of its proper divisors (11023693).

21045171 is a wasteful number, since it uses less digits than its factorization.

21045171 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1002161.

The product of its (nonzero) digits is 280, while the sum is 21.

The square root of 21045171 is about 4587.5016076291. The cubic root of 21045171 is about 276.0900908375.

Adding to 21045171 its reverse (17154012), we get a palindrome (38199183).

The spelling of 21045171 in words is "twenty-one million, forty-five thousand, one hundred seventy-one".