21344237 has 2 divisors, whose sum is σ = 21344238. Its totient is φ = 21344236.

The previous prime is 21344209. The next prime is 21344243. The reversal of 21344237 is 73244312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20967241 + 376996 = 4579^2 + 614^2 .

It is a cyclic number.

It is not a de Polignac number, because 21344237 - 2⁶ = 21344173 is a prime.

It is a super-2 number, since 2×21344237² = 911152906224338, which contains 22 as substring.

It is equal to p_1350359 and since 21344237 and 1350359 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21304237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672118 + 10672119.

It is an arithmetic number, because the mean of its divisors is an integer number (10672119).

Almost surely, 2^21344237 is an apocalyptic number.

It is an amenable number.

21344237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21344237 is an equidigital number, since it uses as much as digits as its factorization.

21344237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 26.

The square root of 21344237 is about 4619.9823592737. The cubic root of 21344237 is about 277.3917528187.

Adding to 21344237 its reverse (73244312), we get a palindrome (94588549).

The spelling of 21344237 in words is "twenty-one million, three hundred forty-four thousand, two hundred thirty-seven".