21871745585065 has 4 divisors (see below), whose sum is σ = 26246094702084. Its totient is φ = 17497396468048.

The previous prime is 21871745585059. The next prime is 21871745585089. The reversal of 21871745585065 is 56058554717812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9382116024576 + 12489629560489 = 3063024^2 + 3534067^2 .

It is a cyclic number.

It is not a de Polignac number, because 21871745585065 - 2²³ = 21871737196457 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21871745584988 and 21871745585006.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2187174558502 + ... + 2187174558511.

It is an arithmetic number, because the mean of its divisors is an integer number (6561523675521).

Almost surely, 2^{21871745585065} is an apocalyptic number.

It is an amenable number.

21871745585065 is a deficient number, since it is larger than the sum of its proper divisors (4374349117019).

21871745585065 is an equidigital number, since it uses as much as digits as its factorization.

21871745585065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4374349117018.

The product of its (nonzero) digits is 94080000, while the sum is 64.

The spelling of 21871745585065 in words is "twenty-one trillion, eight hundred seventy-one billion, seven hundred forty-five million, five hundred eighty-five thousand, sixty-five".