78658561 has 4 divisors (see below), whose sum is σ = 79469572. Its totient is φ = 77847552.

The previous prime is 78658549. The next prime is 78658579. The reversal of 78658561 is 16585687.

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 41216400 + 37442161 = 6420^2 + 6119^2 .

It is a cyclic number.

It is not a de Polignac number, because 78658561 - 2⁵ = 78658529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78658511) 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, 405360 + ... + 405553.

It is an arithmetic number, because the mean of its divisors is an integer number (19867393).

Almost surely, 2^78658561 is an apocalyptic number.

78658561 is the 5121-st hex number.

It is an amenable number.

78658561 is a deficient number, since it is larger than the sum of its proper divisors (811011).

78658561 is an equidigital number, since it uses as much as digits as its factorization.

78658561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811010.

The product of its digits is 403200, while the sum is 46.

The square root of 78658561 is about 8868.9661742505. The cubic root of 78658561 is about 428.4649810921.

It can be divided in two parts, 7 and 8658561, that added together give a palindrome (8658568).

The spelling of 78658561 in words is "seventy-eight million, six hundred fifty-eight thousand, five hundred sixty-one".