78215448181 has 4 divisors (see below), whose sum is σ = 84232021132. Its totient is φ = 72198875232.

The previous prime is 78215448167. The next prime is 78215448197. The reversal of 78215448181 is 18184451287.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18184451287 = 129901 ⋅139987.

It can be written as a sum of positive squares in 2 ways, for example, as 42415402500 + 35800045681 = 205950^2 + 189209^2 .

It is a cyclic number.

It is not a de Polignac number, because 78215448181 - 2⁹ = 78215447669 is a prime.

It is a super-2 number, since 2×78215448181² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78215448131) 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, 3008286456 + ... + 3008286481.

It is an arithmetic number, because the mean of its divisors is an integer number (21058005283).

Almost surely, 2^78215448181 is an apocalyptic number.

It is an amenable number.

78215448181 is a deficient number, since it is larger than the sum of its proper divisors (6016572951).

78215448181 is a wasteful number, since it uses less digits than its factorization.

78215448181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6016572950.

The product of its digits is 573440, while the sum is 49.

The spelling of 78215448181 in words is "seventy-eight billion, two hundred fifteen million, four hundred forty-eight thousand, one hundred eighty-one".