78818281 has 4 divisors (see below), whose sum is σ = 79274052. Its totient is φ = 78362512.

The previous prime is 78818249. The next prime is 78818287. The reversal of 78818281 is 18281887.

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 68475625 + 10342656 = 8275^2 + 3216^2 .

It is a cyclic number.

It is not a de Polignac number, because 78818281 - 2⁵ = 78818249 is a prime.

It is a super-2 number, since 2×78818281² = 12424642839589922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78818287) 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, 227626 + ... + 227971.

It is an arithmetic number, because the mean of its divisors is an integer number (19818513).

Almost surely, 2^78818281 is an apocalyptic number.

It is an amenable number.

78818281 is a deficient number, since it is larger than the sum of its proper divisors (455771).

78818281 is a wasteful number, since it uses less digits than its factorization.

78818281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455770.

The product of its digits is 57344, while the sum is 43.

The square root of 78818281 is about 8877.9660395836. The cubic root of 78818281 is about 428.7547912891.

The spelling of 78818281 in words is "seventy-eight million, eight hundred eighteen thousand, two hundred eighty-one".