78280518581 has 4 divisors (see below), whose sum is σ = 80189799564. Its totient is φ = 76371237600.

The previous prime is 78280518559. The next prime is 78280518587. The reversal of 78280518581 is 18581508287.

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 3660855025 + 74619663556 = 60505^2 + 273166^2 .

It is a cyclic number.

It is not a de Polignac number, because 78280518581 - 2¹⁴ = 78280502197 is a prime.

It is a super-2 number, since 2×78280518581² (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 (78280518587) 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, 954640430 + ... + 954640511.

It is an arithmetic number, because the mean of its divisors is an integer number (20047449891).

Almost surely, 2^78280518581 is an apocalyptic number.

It is an amenable number.

78280518581 is a deficient number, since it is larger than the sum of its proper divisors (1909280983).

78280518581 is a wasteful number, since it uses less digits than its factorization.

78280518581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1909280982.

The product of its (nonzero) digits is 1433600, while the sum is 53.

The spelling of 78280518581 in words is "seventy-eight billion, two hundred eighty million, five hundred eighteen thousand, five hundred eighty-one".