78705281 has 8 divisors (see below), whose sum is σ = 81534600. Its totient is φ = 75919360.

The previous prime is 78705271. The next prime is 78705293. The reversal of 78705281 is 18250787.

It can be written as a sum of positive squares in 4 ways, for example, as 10080625 + 68624656 = 3175^2 + 8284^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78705281 - 2²² = 74510977 is a prime.

It is a super-2 number, since 2×78705281² = 12389042514577922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (78705271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7136 + ... + 14433.

It is an arithmetic number, because the mean of its divisors is an integer number (10191825).

Almost surely, 2^78705281 is an apocalyptic number.

78705281 is the 3968-th centered decagonal number.

It is an amenable number.

78705281 is a deficient number, since it is larger than the sum of its proper divisors (2829319).

78705281 is a wasteful number, since it uses less digits than its factorization.

78705281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21699.

The product of its (nonzero) digits is 31360, while the sum is 38.

The square root of 78705281 is about 8871.5996866405. The cubic root of 78705281 is about 428.5497945852.

The spelling of 78705281 in words is "seventy-eight million, seven hundred five thousand, two hundred eighty-one".