78444561 has 12 divisors (see below), whose sum is σ = 113257968. Its totient is φ = 48273264.

The previous prime is 78444557. The next prime is 78444581. The reversal of 78444561 is 16544487.

It is not a de Polignac number, because 78444561 - 2² = 78444557 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (78444581) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 76855 + ... + 77868.

It is an arithmetic number, because the mean of its divisors is an integer number (9438164).

Almost surely, 2^78444561 is an apocalyptic number.

It is an amenable number.

78444561 is a deficient number, since it is larger than the sum of its proper divisors (34813407).

78444561 is a wasteful number, since it uses less digits than its factorization.

78444561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154752 (or 154739 counting only the distinct ones).

The product of its digits is 107520, while the sum is 39.

The square root of 78444561 is about 8856.8934169945. The cubic root of 78444561 is about 428.0760648137.

The spelling of 78444561 in words is "seventy-eight million, four hundred forty-four thousand, five hundred sixty-one".