21171051 has 20 divisors (see below), whose sum is σ = 34502424. Its totient is φ = 12830400.

The previous prime is 21171049. The next prime is 21171089. The reversal of 21171051 is 15017112.

It is a happy number.

It is not a de Polignac number, because 21171051 - 2¹ = 21171049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21171251) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 10990 + ... + 12771.

Almost surely, 2^21171051 is an apocalyptic number.

21171051 is a deficient number, since it is larger than the sum of its proper divisors (13331373).

21171051 is a wasteful number, since it uses less digits than its factorization.

21171051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23784 (or 23775 counting only the distinct ones).

The product of its (nonzero) digits is 70, while the sum is 18.

The square root of 21171051 is about 4601.2010388593. The cubic root of 21171051 is about 276.6394671733.

Adding to 21171051 its reverse (15017112), we get a palindrome (36188163).

The spelling of 21171051 in words is "twenty-one million, one hundred seventy-one thousand, fifty-one".