21123233 has 4 divisors (see below), whose sum is σ = 21154068. Its totient is φ = 21092400.

The previous prime is 21123211. The next prime is 21123287. The reversal of 21123233 is 33232112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12730624 + 8392609 = 3568^2 + 2897^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123233 - 2¹⁴ = 21106849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123293) 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, 14366 + ... + 15767.

It is an arithmetic number, because the mean of its divisors is an integer number (5288517).

Almost surely, 2^21123233 is an apocalyptic number.

It is an amenable number.

21123233 is a deficient number, since it is larger than the sum of its proper divisors (30835).

21123233 is an equidigital number, since it uses as much as digits as its factorization.

21123233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30834.

The product of its digits is 216, while the sum is 17.

The square root of 21123233 is about 4596.0018494339. The cubic root of 21123233 is about 276.4310328989.

Subtracting from 21123233 its sum of digits (17), we obtain a square (21123216 = 4596²).

Adding to 21123233 its reverse (33232112), we get a palindrome (54355345).

The spelling of 21123233 in words is "twenty-one million, one hundred twenty-three thousand, two hundred thirty-three".