21144307 has 2 divisors, whose sum is σ = 21144308. Its totient is φ = 21144306.

The previous prime is 21144301. The next prime is 21144323. The reversal of 21144307 is 70344112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21144307 - 2¹¹ = 21142259 is a prime.

It is not a weakly prime, because it can be changed into another prime (21144301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572153 + 10572154.

It is an arithmetic number, because the mean of its divisors is an integer number (10572154).

Almost surely, 2^21144307 is an apocalyptic number.

21144307 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144307 is an equidigital number, since it uses as much as digits as its factorization.

21144307 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 21144307 is about 4598.2939227500. The cubic root of 21144307 is about 276.5229312580.

Adding to 21144307 its reverse (70344112), we get a palindrome (91488419).

The spelling of 21144307 in words is "twenty-one million, one hundred forty-four thousand, three hundred seven".