21061237 has 2 divisors, whose sum is σ = 21061238. Its totient is φ = 21061236.

The previous prime is 21061223. The next prime is 21061259. The reversal of 21061237 is 73216012.

It is an a-pointer prime, because the next prime (21061259) can be obtained adding 21061237 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20151121 + 910116 = 4489^2 + 954^2 .

It is a cyclic number.

It is not a de Polignac number, because 21061237 - 2⁷ = 21061109 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21061207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10530618 + 10530619.

It is an arithmetic number, because the mean of its divisors is an integer number (10530619).

Almost surely, 2^21061237 is an apocalyptic number.

It is an amenable number.

21061237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21061237 is an equidigital number, since it uses as much as digits as its factorization.

21061237 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 21061237 is about 4589.2523356207. The cubic root of 21061237 is about 276.1603292015.

Adding to 21061237 its reverse (73216012), we get a palindrome (94277249).

The spelling of 21061237 in words is "twenty-one million, sixty-one thousand, two hundred thirty-seven".