8145215681 has 4 divisors (see below), whose sum is σ = 8256794052. Its totient is φ = 8033637312.

The previous prime is 8145215633. The next prime is 8145215717. The reversal of 8145215681 is 1865125418.

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 3551087281 + 4594128400 = 59591^2 + 67780^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8145215681 is a prime.

It is a super-2 number, since 2×8145215681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8145215581) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55789076 + ... + 55789221.

It is an arithmetic number, because the mean of its divisors is an integer number (2064198513).

Almost surely, 2^8145215681 is an apocalyptic number.

It is an amenable number.

8145215681 is a deficient number, since it is larger than the sum of its proper divisors (111578371).

8145215681 is a wasteful number, since it uses less digits than its factorization.

8145215681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111578370.

The product of its digits is 76800, while the sum is 41.

The square root of 8145215681 is about 90250.8486442094. The cubic root of 8145215681 is about 2012.0288155089.

The spelling of 8145215681 in words is "eight billion, one hundred forty-five million, two hundred fifteen thousand, six hundred eighty-one".