78557461581 has 4 divisors (see below), whose sum is σ = 104743282112. Its totient is φ = 52371641052.

The previous prime is 78557461547. The next prime is 78557461583. The reversal of 78557461581 is 18516475587.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18516475587 = 3 ⋅6172158529.

It is not a de Polignac number, because 78557461581 - 2⁷ = 78557461453 is a prime.

It is a super-2 number, since 2×78557461581² (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 (78557461583) 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, 13092910261 + ... + 13092910266.

It is an arithmetic number, because the mean of its divisors is an integer number (26185820528).

Almost surely, 2^78557461581 is an apocalyptic number.

It is an amenable number.

78557461581 is a deficient number, since it is larger than the sum of its proper divisors (26185820531).

78557461581 is a wasteful number, since it uses less digits than its factorization.

78557461581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26185820530.

The product of its digits is 9408000, while the sum is 57.

The spelling of 78557461581 in words is "seventy-eight billion, five hundred fifty-seven million, four hundred sixty-one thousand, five hundred eighty-one".