81575213065 has 8 divisors (see below), whose sum is σ = 103648506120. Its totient is φ = 61421336832.

The previous prime is 81575213047. The next prime is 81575213081. The reversal of 81575213065 is 56031257518.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 38522697984 + 43052515081 = 196272^2 + 207491^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81575213065 - 2¹³ = 81575204873 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 479854110 + ... + 479854279.

It is an arithmetic number, because the mean of its divisors is an integer number (12956063265).

Almost surely, 2^81575213065 is an apocalyptic number.

81575213065 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81575213065 is a deficient number, since it is larger than the sum of its proper divisors (22073293055).

81575213065 is a wasteful number, since it uses less digits than its factorization.

81575213065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 959708411.

The product of its (nonzero) digits is 252000, while the sum is 43.

The spelling of 81575213065 in words is "eighty-one billion, five hundred seventy-five million, two hundred thirteen thousand, sixty-five".