21300065 has 16 divisors (see below), whose sum is σ = 28000080. Its totient is φ = 15482880.

The previous prime is 21300061. The next prime is 21300077. The reversal of 21300065 is 56000312.

It can be written as a sum of positive squares in 8 ways, for example, as 1014049 + 20286016 = 1007^2 + 4504^2 .

It is not a de Polignac number, because 21300065 - 2² = 21300061 is a prime.

It is a super-3 number, since 3×21300065³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is not an unprimeable number, because it can be changed into a prime (21300061) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1856 + ... + 6785.

It is an arithmetic number, because the mean of its divisors is an integer number (1750005).

Almost surely, 2^21300065 is an apocalyptic number.

It is an amenable number.

21300065 is a deficient number, since it is larger than the sum of its proper divisors (6700015).

21300065 is a wasteful number, since it uses less digits than its factorization.

21300065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8692.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21300065 is about 4615.1993456404. The cubic root of 21300065 is about 277.2002661464.

Adding to 21300065 its reverse (56000312), we get a palindrome (77300377).

The spelling of 21300065 in words is "twenty-one million, three hundred thousand, sixty-five".