78486581 has 4 divisors (see below), whose sum is σ = 78504972. Its totient is φ = 78468192.

The previous prime is 78486553. The next prime is 78486589. The reversal of 78486581 is 18568487.

It is a happy number.

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 71250481 + 7236100 = 8441^2 + 2690^2 .

It is a cyclic number.

It is not a de Polignac number, because 78486581 - 2¹⁰ = 78485557 is a prime.

It is a super-2 number, since 2×78486581² = 12320286794139122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78486589) 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, 905 + ... + 12561.

It is an arithmetic number, because the mean of its divisors is an integer number (19626243).

Almost surely, 2^78486581 is an apocalyptic number.

It is an amenable number.

78486581 is a deficient number, since it is larger than the sum of its proper divisors (18391).

78486581 is a wasteful number, since it uses less digits than its factorization.

78486581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18390.

The product of its digits is 430080, while the sum is 47.

The square root of 78486581 is about 8859.2652629888. The cubic root of 78486581 is about 428.1524862812.

The spelling of 78486581 in words is "seventy-eight million, four hundred eighty-six thousand, five hundred eighty-one".