21126161 has 4 divisors (see below), whose sum is σ = 24144192. Its totient is φ = 18108132.

The previous prime is 21126109. The next prime is 21126169. The reversal of 21126161 is 16162112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-21126161 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21126169) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1509005 + ... + 1509018.

It is an arithmetic number, because the mean of its divisors is an integer number (6036048).

Almost surely, 2^21126161 is an apocalyptic number.

It is an amenable number.

21126161 is a deficient number, since it is larger than the sum of its proper divisors (3018031).

21126161 is an equidigital number, since it uses as much as digits as its factorization.

21126161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3018030.

The product of its digits is 144, while the sum is 20.

The square root of 21126161 is about 4596.3203761270. The cubic root of 21126161 is about 276.4438048180.

Adding to 21126161 its reverse (16162112), we get a palindrome (37288273).

The spelling of 21126161 in words is "twenty-one million, one hundred twenty-six thousand, one hundred sixty-one".