21440369 has 2 divisors, whose sum is σ = 21440370. Its totient is φ = 21440368.

The previous prime is 21440357. The next prime is 21440387. The reversal of 21440369 is 96304412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21049744 + 390625 = 4588^2 + 625^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21440369 is a prime.

It is a super-2 number, since 2×21440369² = 919378845712322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21440389) 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, 10720184 + 10720185.

It is an arithmetic number, because the mean of its divisors is an integer number (10720185).

Almost surely, 2^21440369 is an apocalyptic number.

It is an amenable number.

21440369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440369 is an equidigital number, since it uses as much as digits as its factorization.

21440369 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 21440369 is about 4630.3746068758. The cubic root of 21440369 is about 277.8075760685.

The spelling of 21440369 in words is "twenty-one million, four hundred forty thousand, three hundred sixty-nine".