21171045 has 16 divisors (see below), whose sum is σ = 38712960. Its totient is φ = 9678144.

The previous prime is 21171043. The next prime is 21171049. The reversal of 21171045 is 54017112.

It is a happy number.

It is not a de Polignac number, because 21171045 - 2¹ = 21171043 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100710 + ... + 100919.

It is an arithmetic number, because the mean of its divisors is an integer number (2419560).

Almost surely, 2^21171045 is an apocalyptic number.

It is an amenable number.

21171045 is a deficient number, since it is larger than the sum of its proper divisors (17541915).

21171045 is a wasteful number, since it uses less digits than its factorization.

21171045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201644.

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

The square root of 21171045 is about 4601.2003868556. The cubic root of 21171045 is about 276.6394410396.

Adding to 21171045 its reverse (54017112), we get a palindrome (75188157).

The spelling of 21171045 in words is "twenty-one million, one hundred seventy-one thousand, forty-five".