21133237 has 2 divisors, whose sum is σ = 21133238. Its totient is φ = 21133236.

The previous prime is 21133219. The next prime is 21133241. The reversal of 21133237 is 73233112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20557156 + 576081 = 4534^2 + 759^2 .

It is a cyclic number.

It is not a de Polignac number, because 21133237 - 2⁷ = 21133109 is a prime.

It is a super-5 number, since 5×21133237⁵ (a number of 38 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21134237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10566618 + 10566619.

It is an arithmetic number, because the mean of its divisors is an integer number (10566619).

Almost surely, 2^21133237 is an apocalyptic number.

It is an amenable number.

21133237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21133237 is an equidigital number, since it uses as much as digits as its factorization.

21133237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 756, while the sum is 22.

The square root of 21133237 is about 4597.0900578518. The cubic root of 21133237 is about 276.4746654180.

Adding to 21133237 its reverse (73233112), we get a palindrome (94366349).

The spelling of 21133237 in words is "twenty-one million, one hundred thirty-three thousand, two hundred thirty-seven".