21144437 has 2 divisors, whose sum is σ = 21144438. Its totient is φ = 21144436.

The previous prime is 21144419. The next prime is 21144467. The reversal of 21144437 is 73444112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21104836 + 39601 = 4594^2 + 199^2 .

It is a cyclic number.

It is not a de Polignac number, because 21144437 - 2⁶ = 21144373 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 (21144467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572218 + 10572219.

It is an arithmetic number, because the mean of its divisors is an integer number (10572219).

Almost surely, 2^21144437 is an apocalyptic number.

It is an amenable number.

21144437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144437 is an equidigital number, since it uses as much as digits as its factorization.

21144437 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 26.

The square root of 21144437 is about 4598.3080584058. The cubic root of 21144437 is about 276.5234979654.

Adding to 21144437 its reverse (73444112), we get a palindrome (94588549).

The spelling of 21144437 in words is "twenty-one million, one hundred forty-four thousand, four hundred thirty-seven".