21145417 has 2 divisors, whose sum is σ = 21145418. Its totient is φ = 21145416.

The previous prime is 21145409. The next prime is 21145427. The reversal of 21145417 is 71454112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21123216 + 22201 = 4596^2 + 149^2 .

It is a cyclic number.

It is not a de Polignac number, because 21145417 - 2³ = 21145409 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21145391 and 21145400.

It is not a weakly prime, because it can be changed into another prime (21145427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572708 + 10572709.

It is an arithmetic number, because the mean of its divisors is an integer number (10572709).

Almost surely, 2^21145417 is an apocalyptic number.

It is an amenable number.

21145417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21145417 is an equidigital number, since it uses as much as digits as its factorization.

21145417 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1120, while the sum is 25.

The square root of 21145417 is about 4598.4146181048. The cubic root of 21145417 is about 276.5277699928.

Adding to 21145417 its reverse (71454112), we get a palindrome (92599529).

The spelling of 21145417 in words is "twenty-one million, one hundred forty-five thousand, four hundred seventeen".