78668649 has 18 divisors (see below), whose sum is σ = 114939630. Its totient is φ = 51849216.

The previous prime is 78668641. The next prime is 78668657. The reversal of 78668649 is 94686687.

It is an interprime number because it is at equal distance from previous prime (78668641) and next prime (78668657).

It can be written as a sum of positive squares in 3 ways, for example, as 27225 + 78641424 = 165^2 + 8868^2 .

It is not a de Polignac number, because 78668649 - 2³ = 78668641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 78668595 and 78668604.

It is not an unprimeable number, because it can be changed into a prime (78668641) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 84217 + ... + 85145.

It is an arithmetic number, because the mean of its divisors is an integer number (6385535).

Almost surely, 2^78668649 is an apocalyptic number.

It is an amenable number.

78668649 is a deficient number, since it is larger than the sum of its proper divisors (36270981).

78668649 is an equidigital number, since it uses as much as digits as its factorization.

78668649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1129 (or 1029 counting only the distinct ones).

The product of its digits is 3483648, while the sum is 54.

The square root of 78668649 is about 8869.5348807026. The cubic root of 78668649 is about 428.4832972589.

The spelling of 78668649 in words is "seventy-eight million, six hundred sixty-eight thousand, six hundred forty-nine".