78455581 has 4 divisors (see below), whose sum is σ = 78551964. Its totient is φ = 78359200.

The previous prime is 78455557. The next prime is 78455603. The reversal of 78455581 is 18555487.

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 26687556 + 51768025 = 5166^2 + 7195^2 .

It is a cyclic number.

It is not a de Polignac number, because 78455581 - 2¹⁷ = 78324509 is a prime.

It is a super-2 number, since 2×78455581² = 12310556380095122, which 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 (78455081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46960 + ... + 48601.

It is an arithmetic number, because the mean of its divisors is an integer number (19637991).

Almost surely, 2^78455581 is an apocalyptic number.

It is an amenable number.

78455581 is a deficient number, since it is larger than the sum of its proper divisors (96383).

78455581 is an equidigital number, since it uses as much as digits as its factorization.

78455581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96382.

The product of its digits is 224000, while the sum is 43.

The square root of 78455581 is about 8857.5155094417. The cubic root of 78455581 is about 428.0961094469.

It can be divided in two parts, 784 and 55581, that added together give a palindrome (56365).

The spelling of 78455581 in words is "seventy-eight million, four hundred fifty-five thousand, five hundred eighty-one".