21042161 has 8 divisors (see below), whose sum is σ = 24171840. Its totient is φ = 17943408.

The previous prime is 21042157. The next prime is 21042187. The reversal of 21042161 is 16124012.

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

It is not a de Polignac number, because 21042161 - 2² = 21042157 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21048161) 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 7 ways as a sum of consecutive naturals, for example, 6251 + ... + 9008.

It is an arithmetic number, because the mean of its divisors is an integer number (3021480).

Almost surely, 2^21042161 is an apocalyptic number.

It is an amenable number.

21042161 is a deficient number, since it is larger than the sum of its proper divisors (3129679).

21042161 is a wasteful number, since it uses less digits than its factorization.

21042161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15463.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21042161 is about 4587.1735306177. The cubic root of 21042161 is about 276.0769275518.

Adding to 21042161 its reverse (16124012), we get a palindrome (37166173).

The spelling of 21042161 in words is "twenty-one million, forty-two thousand, one hundred sixty-one".