21161233 has 4 divisors (see below), whose sum is σ = 21611520. Its totient is φ = 20710948.

The previous prime is 21161227. The next prime is 21161237. The reversal of 21161233 is 33216112.

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 cyclic number.

It is not a de Polignac number, because 21161233 - 2⁹ = 21160721 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21161233.

It is not an unprimeable number, because it can be changed into a prime (21161237) 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, 225073 + ... + 225166.

It is an arithmetic number, because the mean of its divisors is an integer number (5402880).

Almost surely, 2^21161233 is an apocalyptic number.

It is an amenable number.

21161233 is a deficient number, since it is larger than the sum of its proper divisors (450287).

21161233 is an equidigital number, since it uses as much as digits as its factorization.

21161233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 450286.

The product of its digits is 216, while the sum is 19.

The square root of 21161233 is about 4600.1340197868. The cubic root of 21161233 is about 276.5966970364.

Adding to 21161233 its reverse (33216112), we get a palindrome (54377345).

The spelling of 21161233 in words is "twenty-one million, one hundred sixty-one thousand, two hundred thirty-three".