21145500065 has 16 divisors (see below), whose sum is σ = 26870700240. Its totient is φ = 15919257600.

The previous prime is 21145500059. The next prime is 21145500071. The reversal of 21145500065 is 56000554112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21145500059) and next prime (21145500071).

It can be written as a sum of positive squares in 8 ways, for example, as 741091729 + 20404408336 = 27223^2 + 142844^2 .

It is not a de Polignac number, because 21145500065 - 2⁴ = 21145500049 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1085915 + ... + 1105215.

It is an arithmetic number, because the mean of its divisors is an integer number (1679418765).

Almost surely, 2^21145500065 is an apocalyptic number.

It is an amenable number.

21145500065 is a deficient number, since it is larger than the sum of its proper divisors (5725200175).

21145500065 is a wasteful number, since it uses less digits than its factorization.

21145500065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32212.

The product of its (nonzero) digits is 6000, while the sum is 29.

The spelling of 21145500065 in words is "twenty-one billion, one hundred forty-five million, five hundred thousand, sixty-five".