21418065 has 12 divisors (see below), whose sum is σ = 37124724. Its totient is φ = 11422944.

The previous prime is 21418063. The next prime is 21418069. The reversal of 21418065 is 56081412.

It can be written as a sum of positive squares in 2 ways, for example, as 10188864 + 11229201 = 3192^2 + 3351^2 .

It is not a de Polignac number, because 21418065 - 2¹ = 21418063 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21418063) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 237934 + ... + 238023.

It is an arithmetic number, because the mean of its divisors is an integer number (3093727).

Almost surely, 2^21418065 is an apocalyptic number.

It is an amenable number.

21418065 is a deficient number, since it is larger than the sum of its proper divisors (15706659).

21418065 is a wasteful number, since it uses less digits than its factorization.

21418065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 475968 (or 475965 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21418065 is about 4627.9655357403. The cubic root of 21418065 is about 277.7112100339.

Adding to 21418065 its reverse (56081412), we get a palindrome (77499477).

The spelling of 21418065 in words is "twenty-one million, four hundred eighteen thousand, sixty-five".