21000233 has 2 divisors, whose sum is σ = 21000234. Its totient is φ = 21000232.

The previous prime is 21000229. The next prime is 21000251. The reversal of 21000233 is 33200012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13454224 + 7546009 = 3668^2 + 2747^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000233 - 2² = 21000229 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21000293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500116 + 10500117.

It is an arithmetic number, because the mean of its divisors is an integer number (10500117).

Almost surely, 2^21000233 is an apocalyptic number.

It is an amenable number.

21000233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000233 is an equidigital number, since it uses as much as digits as its factorization.

21000233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 11.

The square root of 21000233 is about 4582.6011172695. The cubic root of 21000233 is about 275.8934379984.

Adding to 21000233 its reverse (33200012), we get a palindrome (54200245).

The spelling of 21000233 in words is "twenty-one million, two hundred thirty-three", and thus it is an aban number.